Imperial Institute

IMPERIAL INSTITUTE

ONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE PREPARED UNDER THE DIRECTION OF THE MINERAL RESOURCES COMMITTEE OF THE IMPERIAL INSTITUTE WITH THE ASSISTANCE OF THE SCIENTIFIC AND TECHNICAL STAFF

SILVER ORES BY H.

B.

CRONSHAW,

B.A., Ph.D., A.R.S.M,

LATELY f'ROFBSSOR OF GROLOGYj UNIVERSITY COLLEGE, GALWAY

WITH TWO DIAGRAMS AND A MAP

LONDON JOHN MURRAY, ALBEMARLE 1921

Price 6s. net.

STREET, W,

IMPERIAL INSTITUTE

MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE

IMPERIAL INSTITUTE

MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE PREPARED UNDER THE DIRECTION OF THE MINERAL RESOURCES COMMITTEE OF THE IMPERIAL INSTITUTE WITH THE ASSISTANCE OF THE SCIENTIFIC AND TECHNICAL STAFF

SILVER ORES BY H.

B.

CRONSHAW,

B.A., Ph.D., A.R.S.M.,

LATELY PROFESSOR OF GEOLOGY, UNIVERSITY COLLEGE, GALWAY

WITH TWO DIAGRAMS AND A MAP

LONDON JOHN MURRAY, ALBEMARLE STREET, W. 1921

A.LL

RIGHTS RESERVED

O"

IMPERIAL INSTITUTE MINERAL SECTION THE

Imperial Institute

is

a centre for the exhibition and

investigation of minerals with a view . to their commercial development and for the supply of information respecting the sources, composition and value of minerals of all kinds. The Imperial Institute is provided with Research Labora-

and assay of minerals, and undertakes reports on the composition and value of minerals for the information of Governments and producing companies and firms, in communication with the principal users in the United Kingdom and elsewhere in the Empire. Important minerals from within the Empire are exhibited in the respective Courts of the Public Exhibition Galleries, and tories for the investigation, analysis

also in the Mineral Reference Collections of the Institute.

A

special staff

is

and arrangement

engaged in the collection, critical revision' of all important information^ respecting; ,

supplies of minerals, especially within the Enipir^in^w,nietlib<J^ of usage and other commercial developments. :

on these and related subjects are periodically and monoon are special subjects graphs separately published under the direction of the Committee on Mineral Resources. Articles

published in the Bulletin of the Imperial Institute,

461980

IMPERIAL INSTITUTE Advisory Committee on Mineral Resources

The Right Hon. VISCOUNT HARCOURT, D.C.L. (Chairman). *Admiral SIR

EDMOND SLADE,

K.C.I.E., K.C.V.O. (nominated

by

the Admiralty) , (Vice-Chairman). EDMUND G. DAVIS, Esq. *Professor C. H. DESCH, D.Sc., Professor of Metallurgy, University of Sheffield.

*WYNDHAM

R. DUNSTAN, Esq., C.M.G., LL.D., F.R.S., Director of the Imperial Institute. Captain A. L. ELSWORTHY, Intelligence Department, War Office

War Office). W. GREGORY, D.Sc.,

(nominated by the *Professor J.

F.R.S., Professor of Geology,

University of Glasgow, formerly Director of Geological Survey, Victoria, Australia. Sir

ROBERT HADFIELD,

Bart.,

F.R.S., Past-President Iron

and

Steel Institute.

ARTHUR HUTCHINSON,

Esq., O.B.E., M.A., Ph.D., F.G.S., Depart-

ment of Mineralogy, University of Cambridge, W. W. MOYERS, Esq. (Messrs. H. A. Watson & Co., Ltd.). *J. F. RONCA, Esq., M.B.E., A.R.C.Sc., Department of Industries and Manufactures (nominated by the Board of Trade).

'v;

:M.A., B.Sc., Imperial Institute (Secretary). *

Members

of Editorial

Sub-Committet

MINERAL SECTION Principal

Members

of Staff

Superintendent

R. ALLEN, M.A. (Cantab.), B.Sc. (Lond.), M.Inst.M.M. Assistant Superintendent S. J.

JOHNSTONE, B.Sc. (Lond.), A.I.C. Assistants

W.

O.

R.

WYNN,

A.I.C.,

Special Assistant. S.

BANN.

F. H. BELL.

H. BENNETT, B.Sc. (Lond.).

G.

E.

HOWLING,

B.Sc.

(Lond.),

Senior Assistant.

A. T. FAIRCLOTH.

R. C. GROVES, M.Sc. (Birm.), A.I.C. E. HALSE, A.R.S.M., M.Inst.M.M.

PREFACE THE Mineral Resources Committee of the Imperial Institute has arranged for the issue of this series of Monographs on Mineral Resources in amplification and extension of those which have appeared in the Bulletin of the Imperial Institute during the past fifteen years. The Monographs are prepared either by members of the Scientific and Technical Staff of the Imperial Institute, or by external contributors, to whom have been available the statisand other special information relating to mineral resources

tical

collected

and arranged at the Imperial

Institute.

The

object of these Monographs is to give a general account of the occurrences and commercial utilization of the more

important minerals, particularly in the British Empire. No attempt has been made to give details of mining or metallurgical processes.

HARCOURT, Chairman Mineral Resources Committee. IMPERIAL INSTITUTE,

LONDON, S.W.y. July 1920.

vii

CONTENTS CHAPTER

I PACK

SILVER ORES

THEIR OCCURRENCE, CHARACTERS AND USES

:

CHAPTER

i

II

SOURCES OF SUPPLY OF SILVER ORES (a)

BRITISH EMPIRE Europe : United Kingdom Asia : India :

.

.

Rhodesia;

Africa:

/

:

.

Australia

;

;

.

.

.

.

.

Tasmania

New

19

.20

South-

.....

New South Wales

Australia

.

Transvaal; Nigeria;

West Africa N. America : Canada Australasia

.

21

23

Queensland South Western Victoria ;

;

....

;

;

Zealand

CHAPTER

52

III

SOURCES OF SUPPLY OF SILVER ORES (b)

FOREIGN COUNTRIES Europe

:

Austria

:

Germany

Czechoslovakia

;

(including Silesia)

;

France

;

Greece

;

Hun-

;

......

gary Italy and Sardinia Norway Portugal Spain Sweden Asia : Asia Minor; China; Dutch East Indies; ;

;

;

;

Japan Siberia Honduras N. America : Guatemala United States Chile Colombia 5. America : Bolivia

;

80

;

;

;

WORLD MAP OF SILVER DEPOSITS

;

Peru

;

.

....

REFERENCES TO LITERATURE ON SILVER ix

Mexico

;

;

.

69

.

87 126 145

.147

NOTE Numerals :

in square brackets in the text refer Bibliography at the end.

to the

SILVER ORES CHAPTER SILVER ORES

:

I

THEIR OCCURRENCE, CHARACTER AND USES

IN 1918 the British Empire produced 35,189,000 fine oz. which was nearly one-fifth of the world's supply.

of silver,

amount, Canada supplied as much as 21,383,979 oz., or about 60% of the total British production, and 11%

Of

this

of the world's production

The great silver-producing country of Mexico for a long time headed the world's production, but, owing to political disturbances, the output began to fall in 1911, although not to any great extent until after 1913. By 1915 the production had fallen to less than 23,000,000 oz., or about 3,700,000 oz. below the By 1917, however, the output of Canada for that year. conditions in the country had improved and the production rose to 42,020,547 oz., and in 1918 it amounted to as much as 62,517,000 oz.

[i],

In 1919 and 1920 Mexico became the world's chief producer with 75,000,000 and 63,750,000 oz. (estimated) respectively. The United States headed the list as a silver producer in In 1916 her production amounted 1906, and from 1914 to 1918. to 43 of that of the world. The British Empire held the third place from 1905 to 1913

%

inclusive,

and

also in 1917

and 1918, and the second place from

1914 to 1916 inclusive.

Canada where

is

practically the only country of the British Empire proper are mined,, but a very large propor-

silver ores

s

SILVER ORES

;

tion of the silver of that country from ores of lead, zinc, etc.

is

obtained as a by-product

The world's annual production of silver from 1909 to 1913, or for the five years preceding the Great War, averaged about 223,000,000 oz., but from 1914 to 1919 inclusive the average a drop of about 19% as compared For two years the shortage was not felt, owing to large stocks held, and to the comparatively small demand for silver for coinage and other purposes but in 1916 the demand had increased and the stocks had

was only 180,000,000

oz.,

with previous years.

;

become more or less depleted, so that the price began to rise in that year. It continued to rise until it reached as much as 75. 6d. per oz. in February 1920, thus exceeding by 2s. per oz. the intrinsic value of the silver in the coinage of this country.

The to

the

recent unprecedented rise

demand

in

silver'

was chiefly due Far East, first

for the white metal in the

from India, and latterly from China. The Indian demand was supplied first from Shanghai stocks, and at a later date from United States supplies. The export trade from China has increased considerably since 1918, and to meet the balance in favour of China, large shipments of silver have been made from the United States. In March 1920 silver began to decline in price, and by December 1920 it was quoted at about 42 pence per oz., or less than half the price reached the previous February. 1 The fall in price was stated to be largely due to the cessation of bullion purchase by the British Government on India account, to the unfavourable balance of trade against India from July to 1920, to the unfavourable monsoon or lack of rain the summer and autumn of that year, and to the during substitution of paper money for the silver rupee.

December

WORLD'S PRODUCTION OF SILVER The

total world's production of silver from the discovery America up to the year 1919 is estimated roundly to have been about 12,600,000,000 oz. The following table gives the annual productions for various

of

years since 1860 1 The

:

price per oz.

on July

28, 1921,

was 39 pence.

THEIR OCCURRENCE, CHARACTER AND USES

(e)

3

Estimated. [I]

Variations in Average

Annual Production

[2]

of Silver

In the following table the average annual production for periods of ten years (excepting 1911 to 1916), ranging from 1801 to 1916, are given :

The Ratio

of the

Weight

of

Silver produced as

compared

with that of Gold

ratio reached during the period 1851-1860 coincided with the discoveries of gold in California and Australia, which

The low

added

to

the

increase in silver

gold [3],

production,

without a corresponding

SILVER ORES o o o o O O O O O O

MOO O co C M 00 M 00 CO IO

CO ro

N N

^o CO t^

MOO

rfr-

M~

(Nf

M"

CO

Tt-00

C-l

CO

t^

o ^r>- o o t> rj- o O M O ot 0( t^ Of O

o O O

OI o

OOO o
I

rj-oo

t>.

oo

888

O* vO

iO

M

CO M"

M

>ooo

OOOOOOO OOOOOOO M O O O

M O SMTJ-O iO rj-

COt^M

CO

tooooooo OOOOOOOO -^-OIOMOOOO

!O

Tf-

OIOONCOOOCQ

M 04 ON O F^GO O M M O COCO

01

oo

5

O

O^

M"

o

r~~

O o"

10

vo

co

M

10

04

M

VO

O

TJ-

M

cf

o"

o tn co CO O M

10 o t^ IO IO

10

vo ON o\

t^ iO O\

M ^}If)

-

M M

i

oo"

oo"

CO

H H I

CO

O> vO 8M CO 00

M

<S

O"f

O

CO vO 00

00 vO 1

O cooo O O N

1

1000 co

M VO CO o * o

o

fc

oo oo vo" M" o" vO CO 1>

I

M ^t

M

*t-

1

CO N CO -^-vO

O O

vo

1

M O M

O M

V) co

M

of

v>

I

c/)

o

y; C

ppH

CJ

ju

'C (j

^W

l ^^

,T3

13

a

.

cs

da

2 b ,00 "^ _

^U +*

-<S"Sl 5 ^'SS-si^ ^=C^ g J ^3 M ^ S fll

1^11

C

.

eS

t^^O

O

l>

r)-

O

lOOO 00 CO t^-oo

O>

O

ooo>ro t^vo iOO CO t^ M x O> M oo vO cooo O>M 10

THEIR OCCURRENCE, CHARACTER AND USES

C

o .

s.

wI

ills

PH

> 5 o a
O*42 Td

a-y

tf>

_

J2

ft

lllll 8 8 S

8

.S.S.S 8.S

5

U.S.A.

Mexico

Canada Australasia

Peru

PRODUCTION OF CHIEF SILVER-PRODUCING COUNTRIES, 1905-1918. (Millions of Fine Ounces.)

SILVER ORES

8

VALUES OF SILVER The very

ratio of the value of silver to that of gold has varied to time, as will be seen in the table

much from time Thus

below. silver

and Germany the value of have been higher than that of gold. David remarks that: in ancient Arabia

appeared to

Barbour

[4]

"

In the Middle Ages the monetary standard of England was silver, and it was not until the reign of Edward III that a successful attempt was made to put gold coins into circulation,

but from that time both gold and

silver coins continued

to circulate in England, the ratio of exchange between them being declared from time to time by Royal authority. The legal standard of the country continued to be silver, but

coins of both metals were in circulation, and were frequently debased and the ratio of exchange altered."

In the seventeenth century both metals were of equal value in Japan. The variations in ratio between the values of gold and silver in Europe are given in the following table :

Ratio of Value of Gold to that of Silver in Europe at Different Periods [3]

Thus of gold

in 1250, 10*9 oz. of silver were exchangeable for i oz, but in 1911, 38 oz. were required. ;

THEIR OCCURRENCE, CHARACTER AND USES

9

Total Sterling Values of Gold and Silver and Ratio of

Values respectively

World Productions and Values to

1911

ANNUAL VARIATIONS

IN

[3]

of Silver

from 1493

[3]

VALUE OF SILVER

In New York, quotations for silver are given in cents per ounce Troy, 999 fine, but in London they are in pence per ounce Troy, of standard silver, 925 fine. The following table gives the average yearly prices of bar silver in London from 1860 to 1920 :

SILVER ORES

io

THE PROPERTIES OF SILVER white in colour and is capable of taking a In the form of a very fine powder it brilliant polish [5]. It is more malleable and ductile possesses a grey colour.

Pure

silver is

than any other metal except gold, and into exceedingly thin leaves. I sq. mm. in sectional area

may

be hammered

The is

tenacity of silver wire of equivalent to 17-27 tons per

square inch at o C. By hammering or rolling it becomes hardened, but its softness is restored by annealing at about 200 C. It is the most perfect conductor of heat and electricity

known, and

The

specific

this conductivity is increased by annealing. gravity of cast silver is 10-50, whilst that of molten silver is slightly lower and that of precipitated silver Cast ingots of the metal are difficult to prepare slightly higher.

Silver crystallizes in the cubic from minute cavities. in nature. occur but Melting takes crystals rarely system, at about commences volatilization and C. at about 1,000 place of is In the molten state the metal absorbing capable 1,080 C. oxygen from the air to the extent of 22 times its own volume. free

On

cooling, this oxygen is violently ejected. Silver does not oxidize in either dry or moist air at ordinary

temperatures, and only very slightly when the temperature It is easily dissolved by nitric acid, and by hot raised. and concentrated sulphuric acid. Hydrochloric acid attacks

is

It is blackened the metal only slightly. hydrogen, and readily unites with chlorine.

by sulphuretted

THE USES OF SILVER Silver is

mainly used in the form of plate and

with copper Pure silver is

its alloys

for conversion into coin, jewellery. too soft for the production of durable coins, ornaments, and vessels of various descriptions, but this defect may be remedied

The proportion of silver alloying it with a little copper. case of silver articles in the of in 1,000 parts alloy present by is

by their fineness. In Great Britain made of standard silver, the fineness of

indicated

coins are

all

silver

which,

by

of pure legal definition, is 925, but a toleration of 4 units a i.e. silver in 1,000 of alloy is allowed, specimen passes so

THEIR OCCURRENCE, CHARACTER AND USES

n

1 In Germany and long as its fineness lies between 925 and 92 1. in the United States all silver coins, and in France and Austria

the major silver coins, are of fineness 900, with a toleration of 3 units. The minor coins of Austria are of fineness 375 to in all silver coins under i franc contain 835 of France 520 ;

93 of copper, and 72 of zinc in 1,000 parts. The fineness prescribed by law or custom for silver articles is 950 in Great Britain 800 * n France, 750 in North Germany, 812-5 silver,

;

(5)

South Germany, and 820 in Austria. Any silver-copper alloy which contains less than 750 per 1,000 of silver tarnishes very perceptibly in air [6]. Silver bullion is bought by the Mint and manufactured into One coin, which is kept in stock and issued as required. ounce of standard silver, which contains 925 parts of silver in

and 75 parts

of copper per 1,000 of alloy, is converted into silver coin equivalent in value to 55. 6d., whatever may be the

market price of nominal value of

The difference between the and bronze coin and its intrinsic value

silver bullion. silver

is retained by the State to cover the expenses of manufacture and as a source of profit. The worn gold and silver coin which is withdrawn from circulation by the Bank of England and some other banks is received by the Mint at its nominal

value for re-coinage. It is stated that the average deficiency in weight of worn silver coin received at the Mint is 8 to 10%

and the mean age somewhat less than 50 years [7]. Of all the alloys of silver the silver-copper alloys are by The addition of small amounts far the most important. of copper to silver lowers its melting-point, prevents it from effervescing on solidification, enables sound castings to be made, and makes it harder, without sensibly impairing its malleability or altering its colour.

Silver also

alloys with

lead, bismuth, mercury, gold, zinc, and other metals. Electro-plating is carried out in cyanide baths containing

3

oz. of

potassium cyanide and

Oxidized silver

is

about

i oz. of silver per gallon of water.

ordinary silver-copper alloy which has silver sulphide by immersing

been coated with a thin film of

1 The Coins of silver circulation of the United Kingdom is ^60,000,000. a fineness of 500 and of the value of ^5,000,000 were put into circulation in

December

1920.

SILVER ORES

12

sodium sulphide. Silvering calls for the use of thin sheets of silver or of certain compounds of silver.

in a solution of

Amongst the many other uses which have been found for and its compounds may be mentioned the employment

silver

and that of silver oxide for a colour to Silver nitrate in a fused yellow glass. imparting condition constitutes the lunar caustic of pharmacy furof colloidal silver in medicine,

:

thermore,

is

it

used as a marking-ink, as a constituent of

certain hair dyes,

and

is

largely

in

employed

photography

and medicine.

THE SILVER-BEARING ORES Following the precedent set by the United States Geological Survey in its Annual Reports of the Mineral Resources of that country, silver-bearing ores may be grouped under the following heads :

1.

Dry

Siliceous

or

Ores,

comprising gold and silver ores

proper, associated with very small

and

amounts

of copper, lead

zinc.

2.

Argentiferous Copper Ores, with over

3.

Argentiferous Lead Ores, with over

4.

Argentiferous Zinc Ores, with over

2j%

4^%

25%

copper.

lead.

zinc.

of types I to 4. 5. Mixed Ores, comprising mixtures It is clear, therefore, that any account of the occurrence, distribution, and metallurgical treatment of these ores which carry silver must necessarily extend over a very wide field.

Most ores

of lead contain silver,

and the metal

is

frequently

present in ores of zinc and copper, as well as occasionally in ores of iron, nickel, cobalt and bismuth.

SILVER ORES PROPER

more important silver minerals chemical their with composition together

The

following table gives the

:

Native

silver

Argentite Cerargyrite (Horn silver) Proustite (Light-red silver ore) Pyrargyrite (Dark-red silver ore) Stephanite (Brittle silver ore) Polybasite Tetrahedrite (Fahlore) .

....

Ag

Ag2 S AgCl

3Ag2 S.As 2 S 3 3Ag2 S.Sb 2 S 3 5Ag2 S.Sb 2 S 3 9(Ag,Cu) 2 S.Sb2 S 3 3 (Cu,Ag) 2 S.Sb2 S 3

THEIR OCCURRENCE, CHARACTER AND USES

13

In addition to the above, the following are of less frequent occurrence

As 2 S 3

Stromeyerite (Cu,Ag2 )S

:

Freieslebenite,

;

Pearceite, 9(Ag,Cu) 2 S,

;

5(Pb,Ag2 )S.2Sb 2 S 3

;

Embolite, Ag(Cl,Br);

and the gold and silver tellurides, Hessite, Te Petzite, Ag2 (Au,Ag) 3Te 4 Sylvanite, AujjTe^AgaTe and Krennerite, (Au,Ag) 2Te 4 lodyrite,

Agl

;

;

;

;

.

Native Silver. or

foil,

and

Metallic

in strings

silver

occurs

as

coils.

Its

and wiry

lumps, as plate hardness varies

from 2j to 3, and thus, in this respect, it falls bet ween gold that of pure silver being and copper. Density, 10-1 to

n

;

Fresh surfaces are white in colour, but tarnish to a

10-5.

Lustre, metallic ; fracture, The native metal Kobell's 2 hackly. Fusibility, scale). (Von It contains traces of copper, arsenic, antimony and iron.

brown, or blackish colour.

red,

soluble in nitric acid, chloric acid.

is

and gives a precipitate with hydro-

Native silver often occurs in isomorphous admixture with and -mercury, and also with antimony (Dyscrasite). Ag2 S (silver 87%). CrystalArgentite. Sulphide of silver lizes in cubes, octahedra, and rhombic dodecahedra, but also occurs massive. Colour and streak, a dull black or lead gold, copper,

:

Lustre, metallic. Opaque. Cubic cleavage imperfect. Fracture, conchoidal. Sectile. Hardness, 2 to 2j. Den-

grey.

sity,

7 to 7-4.

Fusibility,

1-5.

Yields a globule of

silver

on charcoal. Stephanite,

and

or

antimony,

brittle

or

silver

ore.

A

sulphantimonite of

sulphide silver

;

of

silver

5Ag2 S.Sb2 S 3

It occurs massive, or crystallized in thick 68-36). six-sided tablets, or in short prisms of the orthorhombic system. (silver,

Colour,

iron-black.

Lustre,

metallic.

Hardness,

2

to

2\.

Density, 6-2 to 6-3. Cleavage, brachypinacoidal. Fracture, uneven to semi-conchoidal. Brittle. Before the reducing flame of the blowpipe on charcoal it yields a metallic button. Pyrargyrite, of

silver;

or dark ruby silver ore.

phur 17-82%). and scalenohedral termination. massive.

uneven.

A

sulphantimonite

sul(silver 59-97, antimony 22-21, rhombohedral with columnar short Habit,

3Ag2 S.Sb2 S 3

Often twinned. Also occurs rhombohedral. Fracture, conchoidal to Cleavage, 2 to Brittle. Hardness, Density, 577 to 3.

SILVER ORES

14

Lustre, metallic-adamantine. Translucent in thin splinColour in reflected light, black to grey-black in

5-86. ters.

;

transmitted I

bility,

Streak, red.

Fusi-

Before the blowpipe gives off dense when fused with

(Von Kobell).

antimonial fumes

sodium

deep conchoidal red.

light,

yields a globule of silver carbonate on charcoal.

or

Proustite,

;

light

ruby

silver

A

ore.

3Ag2 S.As 2 S 3

silver:

sulpharsenide

of

arsenic

(silver 65-4, 15-17, sulphur Habit, similar to that of pyrargyrite. Also massive. Cleavage, rhombohedral. Fracture, conchoidal to uneven. Brittle. Hardness, 2. Density, 5-55 to 5-64. Lustre, adamantine. Transparent to translucent. In reflected light, black or grey-black; in transmitted light, almost scarlet-red. Streak,

I 9'43

%)

Heated on charcoal before Fusibility, i (Von Kobell). the blowpipe gives off arsenical fumes (smelling of garlic) ; yields a globule of silver with sodium carbonate. red.

Polybasite.

A

sulphantimonite of silver and copper (silver 62 to 75%, and copper o to 10%). ;

9(Ag,Cu) 2 S.Sb 2 S 3 thin

Habit,

six-sided

tablets

;

also

Colour, iron-black

Lustre, metallic.

;

in

scaly

aggregates.

in thin fragments

by

Cleavage, basal and perfect. Fracture, uneven. Hardness, 2 to 3. Density, 6 to 6-2. Before the blowpipe gives off Fusibility, i (Von Kobell). antimonial fumes with sodium carbonate on charcoal yields

transmitted

light,

cherry-red.

;

a globule of cupriferous

silver.

Cerargyrite, chlorargyrite or

AgCl

(silver

scales

and

horn

silver.

Chloride of silver

:

Habit, cubic, also massive and in Colour, whitish-grey. Lustre, resinous Translucent. Malleable. Sectile. Hardness,

75-3%). plates.

to adamantine. i to 2.

Density, 5-58 to 5-6.

of silver

on charcoal.

Hessite (Ag2Te).

A

Fusibility, i, yielding a globule

telluride of silver.

An

analysis quoted gave 61-0% silver, 38-2% tellurium, and 8% gold. Occurs in small irregular-shaped masses. Colour, lead-grey, sometimes with dark grey tarnish, but usually with bright metallic lustre. It is soft (H,2j), sectile, tough and possesses an uneven fracture. In the closed tube it fuses readily and gives a white fusible sublimate of telluric

by Simpson

oxide.

[8/p.

90],

THEIR OCCURRENCE, CHARACTER AND USES Au 2Te.3Ag2Te).

(Petzite

An

A

telluride

of

15

gold and silver.

analysis quoted by Simpson [8 /p. 91] gave 41-8% silver, As found at Kalgoorlie, tellurium and 25% gold.

33%

this mineral is black in colour, with a bright metallic lustre, which tarnishes somewhat readily on exposure to the air. It is brittle and shows no trace of cleavage. A telluride of gold and silver. Sylvanite (Au,Ag) 2Te 4 An analysis of Higgins gave 36-95 gold, 8-30% silver, and .

%

Possesses a perfect Colour, silver-white. Monoclinic. vertical cleavage and on heating fuses quietly. telluride of gold and silver. Krennerite (Au,Ag) 2Te 4

54-50%

tellurium.

.

A

Very similar in appearance to sylvanite, but possesses a basal cleavage and belongs to the orthorhombic system. Moreover, on heating it decrepitates violently. These are undoubtedly to Kalgoorlite and Coolgardite. be regarded as mixtures of various tellurides and not as distinct species as was supposed by Pittman and Carnot.

"

Broadly speaking, about two-thirds of the world's silver was obtained from base metal ores, and one-third from precious metal ores. Further, only one-fifth, or 20%, was obtained from mines worked exclusively for silver, while fourfifths, or 80%, was derived as a by-product from mines which were worked primarily for one or more of the metals, gold, copper, lead and zinc, and which would not have been in " operation if their silver had been the sole metal output in 1912

[9/P- 185]. _

When oxide

of manganese is largely present in silver-bearing makes them rebellious and difficult or even impossible to treat economically. In numerous silver mines in the Western Mexico and South America, considerable bodies States, of rebellious manganese silver ores have been left unmined ores, it

"

pending the solution of the so-called manganese-silver " problem [9/p. 184], Ores of this type are being investigated in Colorado under the direction of the U.S. Bureau of Mines, and the result is

awaited with interest.

SILVER ORES

16

ARGENTIFEROUS BASE-METAL ORES It is a remarkable fact, as demonstrated by mining experience, that the five metals, silver, gold, copper, lead and zinc, are closely related as regards both the genesis and geological occurrence of their ores. single deposit may contain the

A

two or more

ores of

of the metals in such intimate associa-

tion that they are necessarily mined together, and generally, as in the cases of copper and silver, lead and silver, and gold and silver, retain this association even when reduced to a

metallic condition, and are not separated until the later Instages of metallurgical treatment have been reached.

may be said that it is most unusual to find the ores one of these metals absolutely free from its customary any Silver ores proper yield only a fraction of the associates. world's output of the metal, the bulk being obtained from what are primarily to be classed as lead or copper ores. Under modern metallurgical treatment the precious metal may be economically extracted from ores which are really deed,

it

of

for the production of lead or copper. The silver in these cases constitutes a by-product thus the native copper of Michigan, said to contain at the most i part of silver per 1,000 parts of copper, yielded 509,467 oz. of silver in the

mined

year 1918 as a result of electrolytically refining 56,127,000 Ib. of copper. At Butte, Montana, the copper lodes contain on an average i part of silver per 400 parts of copper, and this It is stated that silver is profitably extracted [lo/p. 163]. there are few deposits in which the ratio of copper to silver is

more than 5,000 Similar remarks

:

i.

may

be applied to the intimate and very

frequent association of silver and lead. It is seldom that a deposit of lead occurs in which the ratio of silver to lead is

than i 10,000. In most deposits the ratio is 1 5,000, but often the amount of silver is much higher [lo/p. 164]. Silver also frequently occurs in deposits which are mined for their gold contents or for both gold and silver. Thus, less

:

:

in the

Kongsberg

given

as

10,000

district the proportion of silver to gold is :

i

;

at Freiberg, from 5,000 to 10,000

:

i

;

THEIR OCCURRENCE, CHARACTER AND USES at Schemnitz

and Nagybanya, from 150 i and at Cripple Creek, i :

Comstock, 24

:

;

to i

I :

:

i

;

17

at the

10 [lo/p. 165].

THE METALLURGICAL TREATMENT OF SILVER-BEARING ORES Silver

Smelting.

alloys

readily

with

lead,

gold,

copper

and a few other metals. Lead and silver obtained in smelting argentiferous lead and other ores are separated in a cupellation

When

furnace.

the

base-bullion

is

rich in silver, the lead is first desilverized

or Parkes' process

in the former

not sufficiently either Pattinson's

by by a series

of fractional

crystallizations, based on the fact that crystals poor in silver separate out from a mother liquor much richer in silver,

until the latter contains

about

2%

The

of silver.

greater portion of copper, nickel or cobalt separates as scum. Parkes' process depends on the greater affinity of silver for zinc than

melted with argentiferous lead, and the a of alloys of lead, zinc and silver, is mixture scum, containing skimmed off, argentiferous lead remaining behind. Zinc

for lead.

is

separated from coarse copper by an electric metallurgical process. Cupriferous and pyritic ores are first roasted and then reduced to matte (a complex-artificial sulphide) from which blister copper is obtained. Oxidized ores may be reduced directly to nearly pure copper. Calcined ores Silver

is

made

to yield a matte, which is calcined and then fused, producing blister copper, or the molten matte is treated in

are

converters.

In pyritic smelting copper matte

is

produced

by smelting raw Blister

pyritic ores in shaft furnaces. copper, reduced from matte, is cast

and subjected to

electrolytic refining.

anodes The electrolyte used into

a solution of copper sulphate in dilute sulphuric acid. The gold and silver collects at the bottom of the tank as a thin is

mud, which

is

screened, dried

and cupelled

;

or

it is

digested

with dilute sulphuric acid. Amalgamation. This may be divided into three classes ores contain(i) Direct amalgamation with mercury alone (for with free mercury and certain ing silver) (2) Amalgamation reagents without roasting. (It includes the Washoe process, :

;

viz.

the combination and the Boss processes)

;

(3)

Amalga-

SILVER ORES

i8

mation with mercury and reagents preceded by a chloridizing roasting. (It includes the Baird, Reese-River, and the FranckTina processes.) The cyanide process has largely replaced the Lixiviation. old Ziervogel, Augustin, Patera, Kiss and Russell leaching processes,

as

process. The ore

is

well

as

the

still

older

patio-amalgamation

crushed fine with cyanide solution (by stamps, by tube-mills). The pulp is concentrated on Wilfley or other tables to remove such substances as tetrahedrite, galena and blende (which are smelted), and is then often

followed

The sand is returned separated into sand and slime. a or is subjected to to the tube-mills lengthy treatment with cyanide in specially-constructed vats. The slime is often treated in a series of tall cylindrical steel vats (Pachuca tanks), with cyanide solution, the pulp being agitated by

compressed

air.

The overflow passes from one tank

to another

until nearly the whole of the silver is dissolved. The metallic silver is precipitated from the clear 'solution either by zinc-

dust or zinc-shavings. The precipitate is screened to get rid of any coarse undissolved zinc, and the screened product, partly dried, is smelted, with the production of silver bullion.

CHAPTER

II

SOURCES OF SUPPLY OF SILVER ORES

BRITISH EMPIRE

(a)

EUROPE UNITED KINGDOM

THE amounts

of silver obtained in recent years in the United Kingdom are as follow

mined

Oz.

1914 1915 1916

No

from ores

:

.

.

.

.

.

.

146,444 96,448 86,485

Or. .

1918 1919

.

.

.

.

.

.

75,472 79,645 68,414

has been mined in the United Kingdom since During 1919 there was a recovery of 134 oz. from 1907. copper ores and 68,280 oz. from lead ores", making a total of silver ore

68,414 oz. [n].

mines were worked in Britain before the invasion Among the Cornish mines which produced be mentioned East Huel Rose lead mine (yield may

Silver

of the silver

Romans.

from 1852 to 1861 was 260,721 oz.), and West Chiverton (yield from 1866 to 1870 was 653,780 oz.). From 1852 to 1881 (30 years) Devonshire produced 31,180 tons of lead and 1,046,085 oz. of silver, but the output diminished rapidly from 1862, and in 1881 had become practically nil. The chief producers were the Tamar silver-lead mine (yield from 1851 to 1863 was 332,204 oz.), and the Frank Mills lead mine (yield from 1857 to 1880 was 247,151 oz.). In 1894 the yield of silver from the North of England, Wales (including Anglesey), the Isle of Man and Scotland amounted to about 260,000 oz. Yorkshire and Derbyshire are not

2O

SOURCES OF SUPPLY OF SILVER ORES

included in the above, as the ores from both are very poor in silver.

Among

the ores of the Parys Mountain, Anglesey, Uuestone it contains 6 oz. 15 dwt. of silver per

of special interest as ton, and appears to be

is

an intimate mixture of galena, blende ore of similar composition, known as kilmacooite, occurs at Avoca, Ireland, and also contains from 6 to 8 oz. of silver per ton [12].

and chalcopyrite.

An

ASIA INDIA the largest consumer of silver in the are worked in the country, the metal being obtained as a by-product in the extraction of lead

Although India

is

world, no true silver ores at

Bawdwin, and of gold at Anantapur. The values and productions of silver from 1909

are given as follow [13]

to 1919

:

The first production of silver in India is recorded for the year 1909. From 1909 to 1914 the entire output given in the table above came from the Bawdwin mines. In 1919, oz., 753 oz. came from Anantapur and from Bawdwin, the former producing since 1915. The net annual average import of silver for the period 1908-13 amounted to over 62,000,000 oz., valued at over

out of 2,165,607 2,164,854 oz.

so

that

the

amount

internally produced, viz. about 104,700 oz., was quite insignificant as compared with the requirements, but recent production has shown a considerable

7,000,000,

increase.

The course of the silver trade ending March 31 is as follows :

of India for three fiscal years

INDIA

RHODESIA

21

During the period May, 1918 to July, 1919, large amounts of silver were imported on Government account from the United States under the Pittman Act. In the year 1918-19 the imports were 122% of the world's production as against a former annual average of 26% [14]. The silver-lead mines of Bawdwin are situated in Tawngpeng, one of the lesser Northern Shan States of Burma. Particulars of these mines are given in the Imperial Institute Monograph on Zinc Ores (pp. 33-4).

AFRICA RHODESIA

No

silver minerals are

amount

known

to occur in Rhodesia, but a con-

of the metal has been

produced by the gold mines as a by-product. The three principal mines, Falcon, Shamva, and Rezende, in 1919 produced 65,491, 24,632 and

siderable

22,952 oz. silver respectively.

Electrum

(gold-silver alloy) is present in a pyritic lode at the It occurs in thin scales associated Filabusi.

Hanover mine,

with pyrite, pyrrhotite, blende, galena, quartz and gold, sometimes being present in the quartz and sometimes in the pyrite.

In the Umtali district a number of gold mines work ores Silver is usually largely or entirely consisting of sulphides. present in galena and blende, and is partly recovered. The Rezende mine, which recovers practically all its silver

from the argentiferous galena, is the most important in the district. The Cairn Dhu mine formerly worked a richly and auriferous arsenopyrite lode, and recovered, argentiferous a few years ago, only 30% of its silver. Samples of arsenopyrite from the Bessie Reef are said to have assayed as

SOURCES OF SUPPLY OF SILVER ORES

22

much

as 50 oz. of silver to the ton, and at the Clutha mine galena is stated to contain up to 400 oz. per ton. It is, moreover, stated that on the Chefamiti claims, Lomagundi, a

lead-copper ore carries both silver and gold in appreciable The copper matte of the Edmundian mine (obquantities. tained from chalcopyrite) carries a few ounces of silver and

3| dwt. of gold per ton. During 1920, the silver production in Southern Rhodesia amounted to 158,982 oz., valued at 58,178, and the total production to the end of 1920 was 2,970,827 oz., valued at 390,828

[15].

TRANSVAAL have been formerly mined to some extent mine in the extreme northern part of the Pretoria-Middelburg area, and at the Transvaal silver mine, where it is associated with copper and lead ores, in the Silver is said to

at the Albert silver

southern portion. Silver-lead ores occur in the lodes south of the Pretoria

road, about 5 miles west of Balmoral [16].

NIGERIA is known to occur small many irregular deposits in the eastern part of Nigeria, from the Afikfo district northwards into the Muri province.

According to A. D. Lumb, silver-lead ore

in

The

from traces up to 125 oz. per ton. and irregular nature of the deposits At Orofu in the Muri province the natives mine lead ore on a small scale, but do not attempt to silver content varies

to the pockety their value is doubtful.

Owing

extract the silver content, which, however,

is

present in small

amount.

SOUTH-WEST AFRICA

[i7/p. 86]

At the Tsumeb mine, Grootfontein

district,

is

a complex

ore deposit consisting of two large, steeply- dipping lenses, in grey Otavi dolomite. The ore of the main bodies, as mined in depth, is a massive coarsely- crystalline aggregate,

of argentiferous galena, chalcocite,

composed and other minerals. The

SOUTH-WEST AFRICA CANADA ore as

exported contains 7-7 oz. silver per ton. Wagner reports [i7/p. 109] that a number of veins carrying argentiferous galena were discovered in 1912 at Aiais, situated a few miles east of the Fish River, in the extreme western portion The country rock is granite, which of the Warmbad district.

by numerous basic dykes, and the veins appear be developed along certain of these dykes. A good deal of exploratory work was done on these deposits during 1912 and 1913 by the South African Territories, Ltd., but as yet it has not been definitely established whether the veins are is

intersected

to

payable or not. Argentiferous galena has also been found near Blydeverwacht, in the south-east corner of the Warmbad district,

and an important occurrence of this mineral was opened up some years ago in the vicinity of Swartmodder in the Maltahohe district.

NORTH AMERICA CANADA silver- producing countries of the world, Canada at present the third place in respect to output. occupies The following table gives the annual productions of silver

Amongst the

for various years

from 1887 to 1920

1

[18]

:

Estimated.

From 1887

to 1893 the production ranged in value between and $300,000 $400,000 and was derived chiefly from Ontario and Quebec. The next three years saw a rapid increase in output, due to the development of the silver-lead deposits of British Columbia, and in 1896 a production of over $2,000,000 is

recorded.

3

From

that year until 1905 the production varied

SOURCES OF SUPPLY OF SILVER ORES

24

between $2,000,000 and $3,500,000, rising rapidly during the next six years to $17,580,455 in 1910, as a result of the discovery of the rich ores of the Cobalt district. there has been a gradual falling off in quantity.

The following

Since then

table gives the production of silver by provinces

from 1909 to 1919

:

Production of Silver by Provinces, 1909-1919 [18]

The percentages

of the total productions for each province

from 1914 to 1919 were as follow

Exports. exports of etc.) in

The silver

ounces

:

opposite gives the recent yearly (metallic, contained in ore, concentrate,

table

:

British Columbia

The

total

amount

of silver produced in British

Columbia

during the year 1919 was 3,403,199 oz., a decrease in amount, as compared with the previous year, of 94,973 oz.

CANADA

SOURCES OF SUPPLY OF SILVER ORES

26

In 1919 the Slocan

the Ainsworth, Slocan, produced about 50% of the

district, including

and Slocan City mining

divisions,

total provincial output of silver, and the Fort Steele mining The division about 6%, all from argentiferous galena. remainder was chiefly derived from the smelting of copper

In all, about 75% of the total proores carrying silver. vincial output of silver comes from the treatment of silverlead-zinc ores,

and the balance mainly from the smelting

of gold- copper ores carrying silver. The table opposite shows the

the

various

districts

production

and mining divisions

of

for

silver

the

in

years

1913 to 1919.

The

following table shows the percentage of silver production from the different mining divisions for the years 1916 to 1919 [21]

I

From

:

the above

seen that the Slocan mining division has by far the greatest output. The largest producers in the Slocan in 1919 were the Surprise, the Bosun, the Queen Bess, and the Standard. The total number of mines shipping from it

is

was approximately forty. on a scale of 50 miles to i inch, showing the distribution of the various mining divisions in British Columbia, is published by the Provincial Department of Mines.

this district

A map,

Drysdale of British

[22] publishes a

that by far the greater 1

preliminary table of classification

Columbian ore-shoots.

number

From

this it

would appear

of such deposits were formed

This includes Trout Lake-Revelstoke 0-68, and others 0-99.

CANADA

27

28

SOURCES OF SUPPLY OF SILVER ORES

during the late Jurassic times, closely following the enormous A few, however, date from intrusions of granites and diorites. times. Tertiary

The mineralized areas in the Kootenay region have probably received more attention from the student of ore-deposits than most other similar areas within the Dominion. dale has

shown that

it is

Drys-

up the Kootenay each characterized by the

possible to divide

into definite metallographic belts, predominance of a particular metal.

Of these the best known

are the gold, silver-lead-zinc, and copper belts respectively, and they may be traced more or less continuously from the

southern to the northern boundaries of the Kootenay district. Furthermore, it happens that the trend and areal extent of the different mineralized belts correspond with definite rock In the case of silver-bearing deposits the followformations. ing relationships have been established [23/p. 62]

:

the ore-deposits themselves are confined to certain ore- zones, which, with the possible exception of replacement deposits, strike either in an easterly or a zones north-westerly direction. The position of these fissure-

Within the

belts,

has been chiefly determined by the intrusion and solidification of granite or dioritic rocks, whilst the filling of the fissures with ore and gangue is to be regarded as the final phase of differentiation, which had yielded This will explain intruded these previouslyigneous rocks. of how it is that the deeply-eroded portions batholiths, and the

some process

of

magmatic

rock- formations, remote from granitic or dioritic intrusives, are seldom productive. The principal ores of this division Division. Slocan

Mining

are complex silver-lead-zinc ores, the mining area being situated

CANADA

29

between New Denver and Silverton on Slocan Lake and Kaslo on Kootenay Lake. The tonnages of high-grade ore and concentrate from the principal shippers of the division in 1918 were as follow Standard Silvertons, 34,727 Van Bosun, Sandon, 27,764 :

;

Roi, Silvertons, 25,278

;

;

Hewitt, Silverton, 19,399

;

Surprise,

Rambler- Cariboo, Rambler, 7,138 Sandon, 13,998 Queen Galena Farm, Silverton, 5,250 No. i, Bess, Sandon, 5,314 Sandon, 1,724. The remaining twenty mines produced 1,515 tons, making a grand total of 142,107 tons shipped. The Standard mine, which for many years has been the leading shipper of the Slocan, has been closed down, but ;

;

;

;

work is being done, so that it may a become large producer again in the near future [18]. Both fissure veins and replacement veins are represented in the district, the latter occurring in the metamorphosed In contrast with the fissure veins, the replacement limestone. veins carry low amounts of silver and lead, and high amounts further development

of zinc. The main vein-fissures generally correspond in strike and dip with the master-joints. Considerable faulting and fracturing along certain axes of folding have taken place so

as to result in a systematic disposition. All transitions exist from true fissure veins, with well-defined walls, to fissure

zones

made up

of a series of interrupted torsional or crevasse-

like fissures, in line or in echelon.

The

fissure

veins

and

zones

may pass into stock-works or a series of connected veins between the hanging and foot- wall fissures [23/p. 56]. An

excellent geological

map of Summary Report

the Slocan mining area of the Geological Survey

is

included in the

of

Canada for 1916 [23/p. 61] Upon it are marked the positions mines and the strike and dip of the lodes. The district is occupied by sharply-folded metamorphosed .

of the

sedimentary rocks, known as the Slocan series, irregularly penetrated by the Nelson granodiorite which is exposed at the surface in large and small areas. The Slocan series is furthermore traversed by numerous offshoots of granite porphyry from the Nelson batholith. The eastern part of " " Kaslo Volcanics the area is bounded by outcrops of the " and the Shuswap Series."

SOURCES OF SUPPLY OF SILVER ORES The various rock-groups and ships are given as follow

Most

their stratigraphical

relation-

:

of the metalliferous veins are contained within those

areas occupied by the Slocan series, which constitutes the roof -rocks of the Nelson batholith and hence, as in most other cases in the Kootenays, stands in intimate relationship to the

igneous intrusion. Slocan City Mining Division. the south

Very

of,

little in

and adjacent the

way

in 1919, but all such

This division

is

situated on

Slocan mining division. of development was done on the claims to,

the

work has given very encouraging

results

[18].

Skeena Mining Division. This is the largest, and as yet important division in the North- Western district,

the most

CANADA

31

due to the operations at Anyox of the Granby Consolidated Mining, Smelting and Power Company, which have had a far-reaching effect on the development of mining principally

in

the coastal region.

The smelting works

at

Anyox were

built primarily to treat the copper ores of the Hidden Creek mines, but also with a view to handling other Granby and

custom

In 1919 ores, silver being recovered as a by-product. the tonnage treated was 647,466 tons this yielded 4,864 :

oz. gold,

oz. silver,

348,408

The Skeena mining

and 19,544,588

Ib.

copper.

division extends for a distance of about

400 miles from Millbank Sound on the south, to the headwaters of the Nass River on the north. It is penetrated by numerous long, narrow inlets and is traversed from Prince Rupert to Terrace by the Grand Trunk Pacific Railway. Considering the undeveloped nature of the region, transportation are unusually good. report on the Alice Arm district

facilities

A

by

J.

M. Turnbull

[21,

1916] indicates that in all probability this district will, in the Three future, rank as an important silver-producing area.

types of deposits containing silver are distinguishable,

viz. (a)

quartz veins of comparatively large size carrying chiefly silver. The ore is essentially a milling-ore. These veins are associated with,

and occur

in,

a rock which

is chiefly

andesite, possibly

The district contains the partly developed Varden and Wolf, and a number of promising mines, Dolly a of similar prospects type, (b) Copper ores, with more or less gold and silver. The characteristic mineralization is pyrite, disseminated and accompanied by a certain amount of diabase

l

in part.

These deposits are less developed and less chalcopyrite. known or understood, (c) Small quartz veins of the fissure type, sometimes containing high silver contents in small erratic shoots. The ore consists of pyrite, blende, galena, chalcoand The country rock cite, ruby-silver, in a quartz gangue. " is the or slate formation." Little argillite development work

has been done on any of these veins.* The Alice Arm mineralized area lies wholly on the eastern 1

Dolerite

is

synonymous with diabase and

is

now more

generally used.

A sample of shipping-grade ore taken from the dump of the La gave 244 oz. silver, 18% lead and 124% zinc to the ton. 2

Rose group

SOURCES OF SUPPLY OF SILVER ORES

32

side of the great Coast Range granodiorite batholith, and is underlaid by a series of various types of metamorphosed

sedimentary and pyroclastic rocks, into which have been intruded various kinds of igneous rocks. The geology of the has not yet been systematically worked out. The Boundary-Yale District. The Boundary- Yale district includes the following mining divisions Greenwood, Grand Forks, Osoyoos, Similkameen, Nicola, Vernon, Kamloops, Ashcroft and Yale. In 1919, the total output of the district was 282,131 tons, which contained silver, 231,599 oz. gold, district

:

;

Ib.

The

ores largely consist of low-grade gold-copper-silver ores.

Two

33,526 oz.

;

copper,

3,835,516 Ib.

;

lead,

77,259

extensive copper-smelting plants were in operation for treatment of these ores one, at Grand Forks, owned by the Granby Consolidated Mining and Smelting Company of Canada, ;

Ltd.,

and the

other, at

owned by the Canada The Granby smelter dealt with

Greenwood,

Ltd.

Copper Corporation, ores from the Granby mines at Phoenix, whilst the smelter at Greenwood dealt with ores which came chiefly from the Mother Lode mine in the Greenwood mining district, but also to some extent from other sources. In 1916, the Granby smelter treated 1,097,299 dry tons of ore, derived from the Phoenix mines, and the following amounts of

metals were obtained

silver, Copper, 15,992,476 Ib. oz nne gld, 36,801 oz. fine. The value in silver and 204,779 gold per ton is given as $0-779, an(^ * ne amount of copper recovered per ton of ore was 14-6 Ib. :

;

-

i

In 1917, the smelter operated by the Canada Copper Corporation, Ltd., at Greenwood, treated 196,856 tons of ore, obtaining 4,247,316

and 46,355

oz.

of

Ib.

of blister-copper, 9,582 oz. of gold, Of the total amount of ore,

silver.

were obtained from the Mother Lode mine, 2,155 tons from the Sunset mine, 243 tons from the Oro The Denoro mine, and 675 tons from the B.C. mine. remainder, 17,391 tons, was derived from various outside I 76,392

tons

sources.

Both smelters

are

now

closed,

and mining

at Phoenix has

ceased in consequence.

Ainsworth Mining Division.

The Ainsworth mining

division

CANADA

33

on the east side of the Trout Lake and Slocan mining divisions, and includes Duncan Lake and the northern portions

lies

Kootenay Lake. The ores mined are largely of the silver-lead type, consisting chiefly of galena with some blende and occasionally a little pyrite and chalcopyrite. Fort Steele Mining Division. The Fort Steele mining of

division occupies the extreme south-eastern corner of British

Columbia

;

its silver

production

is

obtained from argentiferous

galena.

The

mine has produced by far the largest tonnage and is being operated by the Consolidated Mining and Smelting Company. The smelter receipts for the year 1919 show 14,890 tons of silver-lead ore treated, which Sullivan

in the Kootenays,

yielded 126,446 oz. silver. During the same year shipments of argentiferous lead ore amounting to approximately 776 tons were made from the

Eugene property, the yield being 13,383 oz. silver. District. The Coast district includes the mining divisions of Victoria, Alberni, Clayaquot and Quatsino, which are situated on Vancouver Island New Westminster and on the mainland and Nanaimo, which Vancouver, adjacent covers a large area on the mainland, and the north-east coastal belt of Vancouver Island. The ores of the Coast district are of the copper-silver-gold type and essentially of a low-grade character. Usually they consist of magnetite, pyrrhotite, chalcopyrite and pyrite. St.

Coast

;

;

Two

principal types of ore-deposits are distinguishable, viz. the contact-metamorphic type, and the composite lode type. The first of these is represented by ore-bodies which occur in

zones at or near the contact between metamorphosed limestone

These ore-bodies have irregular lensand igneous rocks. shaped outlines and are scattered. In composition they are characterized

by the presence

of magnetite, pyrrhotite, chalco-

pyrite and pyrite in a gangue of garnet, epidote and calcite, with varying amounts of tremolite and hornblende. Those deposits which are situated at the contact contain a higher percentage of magnetite and pyrrhotite, whilst those which occur within the zone of metamorphism, but at some dis-

SOURCES OF SUPPLY OF SILVER ORES

34

tance from the actual contact, contain a higher percentage of

and chalcopyrite. The second type is represented by mineralized shear-zones

pyrite in

rocks.

igneous

Along these

lines

of

disturbance,

the

secondary production of hornblende appears to be common. The ores consist of sulphides of iron and copper, together with magnetite, which varies in siliceous

amount and may be absent, of comminuted country rock.

gangue consisting Mining Division.

in a

Three distinct types of ore-

Victoria

deposits are represented in the division the composite lode type, occurring in shear-zones in the Sooke gabbro, on Sooke

the Tyee type, occurring on Mount Sicker and peninsula the contact type, occurring on Mount Gordon and the Koksilah ;

;

River. Brewer describes several properties which have not, as yet, been adequately developed [21/1916, p. 309]. Alberni Mining Division. Although there are many places

at

which mineralization

occurs

within the Alberni

mining division, only a small amount of development work has so far been carried out, principally due to the low-grade nature of the ore, which contains small amounts of copper, gold and

silver.

Clayoquot Mining Division. Only one group of mines, the Indian Chief group, is reported as having shipped ore in 1919. The mineral localities within this division were examined by

Brewer in 1916 [21/1916,

p. 327].

In manner of occurrence and

the ore-bodies resemble those in the Alberni

composition,

They are essentially low-grade copperores silver-gold consisting of chalcopyrite, pyrrhotite, pyrite and magnetite. The deposits belong to the replacement type mining

division.

and are found within

crystalline limestone

and along shear

The gangue usually consists of garnet, The division is well supplied with safe

zones in igneous rocks. epidote and calcite.

harbours and good wharf sites. Quatsino Mining Division. No shipments of silver-bearing ore were recorded for the year 1919. Up to the present time lode-mining operations are confined to the neighbourhood of the south-east

arm

of Quatsino Mining Division.

Nanaimo Nanaimo mining

Sound

[21/1916, p. 337]. Metalliferous mining in

division at the present time

is

the

chiefly confined

CANADA to

the

northern

portion

of

35

Texada

Island.

During 1919

made from

shipments of copper-silver-gold ores were

several

At the Marble Bay mine, native silver was especially abundant in some of the lower levels far below the zone of mines.

surface enrichment.

It

produced regularly during 1919.

At the Loyal mine the ore-body consists of irregular areas of limestone, and occasionally, dyke rock, replaced by secondary minerals, largely gar net and epidote, with some copper sulphides, The silver content is high, galena, pyrite and magnetite. reaching 20 oz. to the ton. This is probably due to the presence of galena, a mineral not found in the principal producing

mines [27]. Vancouver Mining Division. There are several localities at which very low-grade copper- silver- gold ores occur in composite lodes within highly disturbed schists and igneous rocks. Omineca Mining Division. The Omineca mining division

comprises an extensive territory, something like 58,000 square It miles, in the north-western portion of British Columbia. includes the headwaters of the Skeena, Fraser and Peace rivers, Lakes Tacla, Stuart, Babine and Francois, and the

towns of Hazelton, Aldermere, Fort

St.

James, and Fort

Fraser.

The only portion which has ores

is

the

so far produced silver-bearing Hazelton-Telkwa section. These ores include

both lead-silver and the copper-silver-gold types. As a rule the ore-bodies in the Hazelton-Telkwa district may be considered as small bodies of medium to high-grade ore, as distinguished from the large low-grade ore-bodies found in other parts of the province. For this reason this section should prove attractive to small mining syndicates and individual operators.

In the Hazelton-Telkwa district the important rock-groups are the great series of pyroclastic, extrusive and sedimentary rocks known as the Hazelton formation the intrusive grani;

toid rocks known as the Bulkley eruptives, coal- bearing

and the sedimentary,

Skeena formation.

The rocks of the Hazelton formation consist of quartzites, argillites and schists, as well as partly altered volcanics, and a third class of pyroclastic rocks.

Mineralization has taken

SOURCES OF SUPPLY OF SILVER ORES

36

place in the Hazelton formation or in the Bulkley eruptives at points not far removed from the contact. Shearing and fissuring of the country rock accompanied the intrusion and Mineralization represents the last cooling of the eruptives.

phase of the granitoid intrusives. The dykes associated with the plutonics are probably either contemporaneous or but slightly antecedent to the mineralizing phase. The Bulkley eruptives are usually granodiorite, but true diorite

and quartz- diorite are often seen. Wide variations and texture are found in different places, but

in composition

all points the rocks are easily identified. Attendant dykes of felsite, granite porphyry, etc., are common. Throughout the district many different types of ore-bodies

at

are to be found. are

The

principal types of wide distribution lodes accompanied by replacement, in

composite " true fissure vein type," (b) simple lodes, or the and (c) metasomatic deposits. From the point of view of mineral contents the ore-deposits of the Hazelton-Telkwa district may be broadly divided into two groups, which, however, grade into one another. One :

(a)

shear- zones

;

the copper- silver- gold group, and the other the lead-zincThe predominating minerals in the first group silver group. is

are chalcopyrite, pyrite, arsenopyrite, pyrrhotite, and bornite, and in the second, galena, blende, tetrahedrite, stibnite, and very subordinate amounts of chalcopyrite, pyrite, arsenopyrite

and native

As a

silver.

rule the silver content is at

but higher and lower ratios than this are common. Usually the blende does not carry much silver. Tetrahedrite, on the other hand, is nearly Stibnite, found principally in the always high in silver.

least i oz. to the unit of lead,

claims of Nine- mile Mountain, stands in to silver content as does galena.

much the same relation

properties of the district were examined by in 1916 [21/1916, p. 92]. Galloway small amount Windermere and Golden Mining Divisions.

The mineral

A

of silver is obtained

from

silver-lead ores occurring in the division. At the Paradise mine, in

Windermere- Golden the Windermere mining

division, the ore

probably replaces limestone in a sheared zone between limestone and quartzite.

CANADA

37

From

a shipment in 1919 some 2,000 tons of ore from an lead and 25 oz. silver per ton were average of about 25 At the Lead Queen the country rock is quartzite, obtained. and the ore, which is galena, is stated to contain 30 to 40 oz.

%

per ton in silver, and from 65% lead. These examples are fairly typical of other ore-bodies, which are at various points Some of these are described in the within this region.

annual reports on the Mineral Production of Canada [18]. The silver production of this Trail Creek Mining Division. division is confined to the Rossland mining camp, which is described by Drysdale [28] and by Bruce [21/1916, p. 214]. The following three groups shipped gold- silver- copper ores during 1916 to 1918 :

From 1894

to 1914 the total production in silver of the to 1,148,362 oz.

Le Roi group amounted

From 1894 to 1914 the total production in silver of the Centre Star- War Eagle group was 1,082,499 oz The ore from the Centre Star claim itself would perhaps average 0-6% -

copper, 0-3 oz. silver and $7 to $10 in gold per ton. At the town of Trail are situated the extensive smelting and refining plants of the Consolidated Mining and Smelting Co., of

Canada, which produce the following refined metals

:

gold, silver, copper, zinc, lead, as well as copper sulphate, sulphuric acid and compounds of arsenic and antimony. Since

the

company took over the plant in 1894, over 5,000,000 tons of ore had been treated up to 1917, with a gross yield of 27,500,350 oz. of silver. In addition to the ores from Rossland, a large tonnage of custom ore is treated.

The Rossland area is occupied by a complex of igneous rocks of Carboniferous age, designated the " Mount Roberts Formation." The igneous rocks include augite-porphyrite, of

Carboniferous age, monzonite, Nelson granodiorite, and

SOURCES OF SUPPLY OF SILVER ORES

38

pulaskite, along with

minor intrusions of porphyry and lam-

prophyre.

The Rossland pyrite,

ore consists mainly of pyrrhotite and chalcoassociated with a gangue of altered country rock,

containing some quartz, and locally a little calcite. The oredeposits of the producing belt at least are replacement lodes, along fissures and shear- zones. In the South Belt and within the augite- porphyry are lodes of pyrite and marcasite, with Silver may be the most important metal in arsenopyrite.

such lodes. The Nelson Mining Division. The three principal mining areas within this division are the Ymir, Sheep Creek and Nelson

The most important properties are described in the Annual Reports on the Mineral Production of Canada [18],

camps.

whilst Drysdale deals with the detail [22]. The ores are of various types lead-silver,

and

Ymir Camp

in considerable

and include those

of gold-silver,

gold-silver-copper.

In the Ymir area the lodes occur in the granitic rocks of the Nelson batholith, in small intrusions of monzonite, and within the metamorphic rocks of the Pend d'Oreille and Rossland groups. The ores containing silver essentially consist

and blende. Some of these ores contain At gold. present very little mining is done in the Ymir Without doubt many undiscovered veins are still area. hidden under the thick cover of wash and drift in certain promising belts. It is recommended [22/p. 62] that veins parallel to those of the main producers of the past should be sought after and many of the abandoned barren veins should of galena, pyrite

be

tested

further

for

the

occurrence

of

ore- shoots

at

geologically favourable localities. South-Eastern Cassiar. An account

is given [24/p.7o] of the of a Camsell results geological reconnaissance, by carried out in 1915 in the little-known region, lying north of

C.

the Grand Trunk Pacific Railway, and between 124 and 126 This region includes the basins of long, and 54 and 56 lat.

and Takla lakes of the Fraser River drainage of the Omineca, Manson and Nation and the headwaters system, Stuart, Trembleur, rivers of the

Peace River system.

CANADA

39

Parts of the area investigated showed evidence of important mineralization and are worthy of more serious attention.

Although veins are

fairly

high-grade gold- and silver-bearing quartz

known to occur, no lode mining has yet been attempted

owing to the high cost of transportation.

Camsell considers

that portion occupied by the slates, schists and associated rocks of the Omineca district as presenting the most favourable conditions for the occurrence of ore deposits. These rocks are penetrated by igneous intrusive rocks and are traversed by mineralized veins of quartz.

Ontario

The

silver

produced in Ontario

is

obtained from silver-

cobalt-nickel ores occurring in narrow, but rich veins, closely associated with sills of quartz- diabase which are intruded into

a complex of rocks of pre-Cambrian age. Most of the silver comes from the immediate neighbourhood of the town of

amounts are also produced at Gowganda The following are the productions of from the four mining districts of Ontario, and from

Cobalt, but small South Lorrain.

in

silver

by-products in 1919

:

....

Fine Oz.

Cobalt Casey Township

Gowganda South Lorrain Recovered from gold ores

.

nickel-copper refining

Total

10,315,889 171,278 722,564 4,586 92,675 56,260

.

From 1866 to 1903 considerable quantities of silver were obtained from the district about Port Arthur, Lake Superior, and particularly from the Silver Islet mine situated on a small Lake Superior, and abandoned in 1884, work had been carried to a depth of 1,160 feet, and it is estimated that $3,250,000 of silver had been extracted [30]. Below is given a list of the mines or companies which, in 1919, produced more than a quarter of a million ounces of

island f mile from the western shore of near Port Arthur. When the mine was

4

SOURCES OF SUPPLY OF SILVER ORES

40 silver

with their individual contributions.

Unless otherwise

indicated, these mines fall within the Cobalt district proper.

Other producing

mines in 1919 were Adanac, ChamTemiskaming, Provincial, Silver Queen, Crews-McFarlan (Gowganda), Tretheway, Green Meehan, Foster, Hargrave, Hudson Bay, Copper Cliff, Penn- Canadian, Peterson Lake, Currie, Right- of- Way and Waldman. Table I (p. 41) gives the shipments of ore, concentrate and silver bullion from the Cobalt silver mines from 1909 to 1919. The figures take no account of inter- camp movements, but include all shipments to outside points, whether in Ontario or the United States. The diminution in raw ores sent out, and the increase of concentrate and bullion will be noted. Table II (p. 42) shows the quantity and value of all the silver

:

bers- Ferland, Keeley,

constituents

Cobalt

recoverable and recovered, in

the ores of the

since 1909. At the beginning of the silver-mining industry, in 1904, the entire output was sent to smelters in the United States. After-

camp

wards concentration methods were introduced, which were followed

by the establishment of refineries within the province. At a number of the mines themselves, smelting and cyanidation processes were introduced for the production of merchantable bars, and custom concentration and reduction plants were

As at the Nipissing mine, special methods of ore treatment were devised, and the introduction of the flotation process enabled large quantities of low-grade material to be concentrated. Out of the total quantity of silver contained in the product of the cobalt mines in 1917, namely 19,401,893 oz., 14,504,681 oz. were refined at the mines in Cobalt or in Ontario works, being about 75% of the whole. The silver-cobalt The refineries in operation during 1919 in Ontario were erected.

:

CANADA OO

OWi

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rfOOO M O COTft^(^COu-> O > t^ CO COOO >O N ^O O 00 00 t^ t^OO OO ''f CO (N

*-"

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41

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COO O co O " >oco o >o >o ^JON IOCOO CO 1000" rfoo" N" M" M~O ONO O O > O. O O coo 10 r^o N -rt-oo o co o" o" W- co t-T ^- ON

M N o t^ >O >OO

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SOURCES OF SUPPLY OF SILVER ORES

CANADA

43

Deloro Smelting and Refining Co., Ltd., at Deloro the Reduction at Thorold the Metals Co., Ltd., Coniagas Chemical, Ltd., at Welland, and the Standard Smelting and ;

;

Refining Co., Ltd., at Chippawa.

Results of Operations of Ontario Silver-Cobalt Refineries, 1919

[29]

In Cobalt camp itself, the Nipissing, O'Brien and Buffalo mines produce bullion from their own ores, and the first-named There are two plants which also from purchased ores. concentrate ores purchased for the purpose, or act as custom concentrators. These are the Dominion Reduction Co., and The former the Northern Customs Concentrators, Ltd.

produces bullion, the latter concentrate only. In 1919, the various reduction works at Cobalt produced 1,666,135 oz silver. -

The silver deposits at Cobalt, Gowganda, Shiningtree Lake and The at other points, are associated with sills of quartz-diabase. veins on Florence Lake, which carry no silver and only traces of cobalt, but a considerable amount of chalcopyrite and quartz

rather than calcite, are associated with a sill which is partly The veins occurring in North Williams, a quartz-norite. Dufferin, and Browning townships, containing a little smaltite, cobalt bloom, stibnite, galena, etc., and little or no silver, are also associated with a sill intermediate between a quartzdiabase and a quartz-norite. As far, then, as present experience

SOURCES OF SUPPLY OF SILVER ORES

44

in northern Ontario goes, typical silver cobalt veins are to be expected in association with sills of quartz-diabase and not

with

sills

rock-types

of quartz-norite. is,

The

distribution of these

two

accordingly, a matter of economic importance

[3I/p. 121]. Cobalt District.

due north of

The Cobalt district lies about 330 miles Toronto, and midway between Lake Ontario and

Hudson Bay. According to the geological maps published by the Department of Mines of Ontario, the district is occupied by those subdivisions of the pre-Cambrian designated the Keewatin and Lower Middle Huronian formations, which conglomerates, quartzites and various members These rocks are cut by intrusions of a metamorphic complex. of diabase, and in places are overlaid by Niagara limestones. The more common minerals of the remarkably rich veins mined in the Cobalt district are the arsenides of cobalt and nickel, smaltite with some Moanthite, cobaltite and niccolite, consist of

associated with native silver.

Less frequent are native bismuth, pyrargyrite, proustite, dyscrasite, argentite, millerite, with occasional arsenopyrite and tetrahedrite. Pyrite, galena and found sometimes in wall the The gangue rocks. blende are minerals are calcite with a little quartz, but both are subordi-

nate constituents in the rich parts of the veins. Calcite veins often serve as leaders which are followed in searching for the

The cobalt-bearing veins are indicated at the " the pale reddish- blue colour of cobalt bloom." by great majority of the veins are very narrow cracks, each

valuable ore. surface

The

a fraction of an inch in width, filled with calcite. They are generally vertical, but seem to be rather irregular in strike, and pass without interruption from the Huronian into the underlying Keewatin. Also they traverse the intrusions of For considerable distances they may be quite barren diabase. of metallic minerals, and may pass into a series of parallel Portions rich in ores fractures, one of which will carry ore.

may be from

4 to 8 inches in width, and, in exceptional cases, foot for short distances, carrying a solid mass of a more than cobalt and nickel arsenides, more or less impregnated with native silver, and with a rather subordinate

mostly

calcite

with sometimes a

little

amount

quartz.

of gangue, linear

The

CANADA

45

extent of the pay portions of the veins is not great and does not generally exceed a few hundred feet. The very rich ore, which carries 2,000 to 6,000 oz. per ton, does not extend, as a

more than 200 feet in depth. seems probable that the veins at Cobalt, as they exist at the present day, represent merely the roots of what was formerly a much more extensive system. Denudation has appa-

rule, It

rently removed the upper portions. The genesis of the minerals is evidently bound up in an intimate fashion with the intrusion It is interesting to of the post-Huronian diabase eruption. note the similarity of these deposits with those of Kongsberg in

Norway

[32].

Gowganda.

The

first- discovered

silver- bearing

vein in the

Gowganda Lake in 1908. Gowganda district was The production during 1919 from the district amounted to 722,564 oz., of which the Miller Lake O'Brien mine produced 708,872 oz. The discovery of high-grade silver ore on the O'Brien property at Miller Lake was made in 1916, and during found east of

1917 the Gowganda district received considerable attention from mining companies in search of new properties, no In the same year doubt as a result of this discovery. from was recorded the Reeve-Dobie a small production mine.

The Gowganda mining

division forms a part of the great

pre-Cambrian peneplain of northern Canada and is occupied by a complex of gneisses, schists and igneous rocks, whose stratigraphic relations are given as follow [33]

:

Unconsolidated

Pleistocene

cial

till,

glastratified

clay and sand.

Post-Huronian intrusions

.

OH vine diabase, quartz diabase

f

Huronian

and

aplite.

Lorrain series (Upper or Middle)

Quartzite, arkose and quartz conglomerate.

Cobalt series (Middle or Lower)

Conglomerate, greyslate and wacke,

K

Pre-Cambrian I

arkose.

Rhyolite and rhyolite tuff.

Great unconformity.

SOURCES OF SUPPLY OF SILVER ORES

46

Laurentian

batholithic

trusions

.

.

in.

Hornblende and biotite granites,

grano-

diorite and syenite their gneissic

and Pre-Cambrian

(con-

equivalents.

^

United)

Keewatin

.

.

.

Basic and acid volcanic and intrusive rocks, and various schists.

The

basement and mantle of Huronian sediments by dykes and sills of quartz-diabase and quartzAs a rule the dykes do not exceed 100 feet in width attain thicknesses up to 500 feet or more and are many

crystalline

are penetrated norite.

the

sills

;

The dykes are vertical, square miles in horizontal extent. in the crystalline basement than the

m

and more numerous Huronian formation.

The

on the contrary, are found Between quartz-diabase and only within the Huronian. quartz-norite all intermediate gradations are to be observed. sills,

An exhaustive study of the various modifications included under the head of quartz- diabase has led Collins [3i/p. 97] to the conclusion that a quartz- diabase magma gave rise to the following differentiation products (1) A diabase series.

:

(2)

An

(3)

Calcite.

(4)

Quartz- calcite veins carrying silver, cobalt and other with the diabase sills.

aplite series.

ores, that occur along

Practically all the

quartz-diabase 2 feet wide

sills.

veins at

They

and usually

or nearly so.

any common

less

Gowganda occur within

the

are sharply-defined fissures rarely

than one

foot.

The dip

is

vertical

Generally speaking, there does not appear to be trend to the veins in any one area or in the

region as a whole. The veins contain

native silver, smaltite, niccolite, and in a gangue of calcite and quartz. Native bismuth, chalcopyrite pyrite, specular haematite, stibnite and galena are less constant

The carmine stain of cobalt bloom is one of the constituents. most conspicuous signs whereby the veins may be recognized. The mineral

constituents of the veins are believed to represent a late differentiation product from the quartz- diabase magma.

CANADA

47

South Lorrain. The production of silver for the year 1919 South Lorrain amounted to 4,586 oz., the chief operating company being the Pittsburg-Lorrain Syndicate, working on the Currie mine. The Keeley mine, formerly one of the chief in

producers, has been reopened and an 80- ton mill constructed.

The manner

is

being

of occurrence of the ore deposits within the is similar to that at Cobalt. The veins

South Lorrain area

occur chiefly in the diabase and in the Keewatin near the contact with the diabase.

Quebec

The small quantity is

obtained from

of silver recorded as produced in Quebec the pyritic ores mined at Eustis and Weedon,

in the Eastern Townships,

Dame

and the lead-zinc ores of NotreThe productions for the

des Anges, Portneuf County.

years 1915-1920 were respectively

142,829

;

127,223

;

and 57,514

:

78,809

;

58,054

;

96,620

;

fine oz.

Yukon The annual productions of silver from 1909 to 1919 are given below

Yukon

for the years

:

[18]

The

greater part of the total output is derived from alluvial workings, the rest being recovered from the gold and copper ores of Whitehorse and the silver-lead ores shipped from

In the former case the silver occurs alloyed with the On an average, about one ounce of silver is placer gold. contained in each 5 oz. of crude bullion from the alluvial In 1916 about 13% of the total output was workings.

Mayo.

SOURCES OF SUPPLY OF SILVER ORES

48

contributed by lode mining. In 1909 the whole of the silver was derived from placer deposits, the first output from lodes

being in the following year.

Mayo Area (Duncan Mining Division). This area includes Mayo on Stewart River, and lies within the western

the town of

Duncan Creek mining district. Cairnes examined and reported on the area in 1915 [24/p. 10], So far, prospectors have been mainly occupied with placer deposits, with the result portion of

that very inadequate attention has been given to the occurrence of lodes. In addition, there is a heavy mantle of superficial

which obscures the underlying bedrock in most This bedrock mostly consists of mica-schists and places. quartzites, with crystalline limestones, and is believed to be deposits,

At certain points intrusions by granite, and rhyolite, greenstone have taken place. The most important lode deposit so far discovered is a rich silver-lead vein on Galena Creek. Other veins are known but in most carrying gold, silver, lead and zinc minerals cases they have not been developed, and very little is known of

pre-Cambrian age.

;

concerning them. Galena Creek. The ore of this mine consists chiefly of galena and ruby silver, with pyrite. Samples assayed at the Govern-

ment Assay

Office,

Whitehorse, Yukon, were found to contain

:

Whitehorse Mining District. In this district silver is recovered from gold and copper ores. The latter are chiefly associated with magnetite and generally occur as contact-

metamorphic deposits in limestone at its contact with granite. Conrad Mining Division. The Conrad mining division lies on the northern side of the Atlin mining division of Northern British Columbia, although, geologically speaking, the two divisions are inseparable.

the

Wheat on

area and the

Two subdivisions Windy Arm area.

are recognized,

CANADA

49

Wheaton Area. Practically the entire area is believed to be underlaid by the granite rocks of the Great Coast Range batholith, which outcrop over the greater part of the area. In addition, there are various groups of sedimentary, metamorphic and igneous rocks. The following is given as the stratigraphic relations of these rock-groups .

Formation.

Kainozoic

Wthological character.

Various volcanic rocks and minor intrusive rocks, with tuffs and

.

breccias. C

Coast Range intrusive rocks.

Laberge

Mesozoic

series

to the

The

corresponds

Kootenay

.....

Pre-Cambrian

viz.

Shale,

sandstone, ~arkose,

grey-

wacke, conglomerate and brec-

Probably Palaeozoic

and dioritic intrusive rocks, volcanic rocks with tuffs and breccias.

Granitic

(?).

Mt. Stevens group

.

Conglomerate with sandstone, shale, and seams of coal. Limestone, pyroxenite.

Various schists and gneisses.

silver-bearing ore deposits are of three principal types,

:

(a)

Gold-silver veins.

(b)

Antimony-silver veins.

(c)

Silver-lead veins.

Veins of the gold-silver type are widely distributed in Southern Yukon. The more important occur on Mount

Mount Stevens, Wheaton Mountain, Gold Hill, and along the south side of Watson River to the north of Hodnett Mountain. The ore-bodies are chiefly in the coast range intrusive rocks, but also in the schistose members of the Mount Stevens group. Within the granitic rocks the where the deposits are generally of the simple lode type Anderson,

;

country rock is made up of schists, however, the gold-silver ores have been deposited in lens-shaped masses and irregular

The most important constituent is galena. Pyrite and chalcopyrite occasionally exist in small amounts. The gangue consists of quartz, with which is usually associated calcite in subordinate amounts. The most important mines

fissures.

'

SOURCES OF SUPPLY OF SILVER ORES

50

so far prospected are the Buffalo the Whirlwind, all of which lie

Hump, within

the Tally-Ho and the big bend of

Wheaton River. The antimony-silver

veins occur chiefly on the western or north-western slope of Carbon Hill facing Wheaton River. The country rock is for the most part the Coast Range granitic intrusive,

but occasional veins are found

in

the

Mesozoic

andesitic rocks, which are older than the former. The mineral contents are stibnite, galena, tetrahedrite, blende, and in some cases arsenopyrite, together with quartz and smaller

and barytes. Some of the lodes contain of silver, but these are amounts important generally low in antimony, and those rich in antimony are as a rule low in silver. In a few places, however, both silver and

amounts

of calcite

antimony occur together

in important amounts. Veins of the silver-lead type are limited in their occurrence in the Wheaton district, so far as is known, to one small area situated on the east slope of Idaho Hill, facing Annie Lake.

doubtful whether, under existing conditions, they are of any considerable economic importance. Windy Arm Area. The southern portion of this district, It is

the

Windy Arm

area,

was described by Cairnes

[23/p. 34] in

1916.

Caribou, a point on the White Pass and Yukon Railway, serves as a distributing centre for the Windy Arm area. All the properties are quite readily accessible and practically all are situated at distances of from J to 4 miles from Windy and at elevations of from 1,200 to 3,600 feet above it. aerial

tramways

for

Arm, Thus

conveyance of ore to the water's edge for

shipment or treatment have been or can be readily constructed. The ores chiefly consist of pyrite, galena, arsenopyrite, pyrargyrite and argentite, in a gangue of quartz, and generally carry fairly high amounts of silver and gold. Locally, the country is made up of porphyrites, andesites, basalts and tuffs, which comprise a portion of the Windy ArmConrad series. The ore deposits are fissure veins, which,

with one exception, intersect andesitic rocks. The exception is the Big Thing, which is about 5 J miles almost due south of Caribou. The ore occurs in a fissure vein which

CANADA

51

intersects granitic rocks of Jurassic or Cretaceous age, and is composed dominantly of quartz, pyrite and some disseminated

arsenopyrite, as well as occasional particles of chalcopyrite, galena and stibnite. The vein, which is usually 2 to 8 feet in thickness, although in places it becomes as much as 12 feet thick, of value for its gold content, but also contains some

is chiefly

The Montana mine is situated about 3 miles south of Big Thing. The ore occurs in a fissure intersecting basalts, andesites and related rock-types, thought to be of Cretaceous or Jurassic age. The M. and M. vein outcrops on the left bank The vein occurs as of Pooly canyon near the top of the hill. a fissure in andesite, and is in most places from 6 to 12 inches in thickness. The ore consists of pyrargyrite, stephanite, freibergite, tetrahedrite, and blue and green copper carbonates silver.

gangue of quartz. This deposit is especially rich in silver. Venus No. i and Venus No. 2 are adjoining properties. A considerable amount of mining has been carried out on the

in a

latter.

Some small shipments

of ore

were made in 1916

;

the ore consists mainly of galena, pyrite and some jamesonite, yukonite, chalcopyrite and chalcocite in a gangue of quartz.

The gold and

vary greatly. In most places the vein carries from less than one ounce to over 100 oz. of silver per ton, and from a trace to about $100 in gold. silver contents

ore is unaltered, it contains up to 15% lead, and from a trace to nearly i% copper. A shipment of 300 tons of sorted ore averaged about $70 per ton. The vein occurs as a fissure traversing andesites, and the mineral contents have a banded and comb structure. To a certain extent, replace-

Where the

ment of the wall rock has also occurred. The Dail and Fleming group comprises a number of claims located along the west side of Windy Arm, immediately to the south of the Venus No. 2. Three principal veins have been found, known as the Venus, Humper and Red Deer, respectively.

The Venus vein Venus No. 2 mine.

the same as the one developed on the In the weathered portion, pyrite, arsenopyrite, galena, yukonite, together with realgar and orpiment are noted as occurring. The average silver content is believed is

to be generally under 10 oz. per ton, but varies from less than

SOURCES OF SUPPLY OF SILVER ORES

52

an ounce to over 100 oz. The gold content averages in value about $15 per ton, whilst that of the lead ranges from about $i to $30 per ton. The Humper vein andesitic rocks.

is

The

the fissure

of

type

thickness of the vein

is

and traverses from 10 to 24

inches in most places where explored, and the ore consists of argentite, pyrargyrite, stephanite, galena, pyrite and some native silver in a gangue of quartz. Parts of the vein, at least, are

very rich in

The Red Deer vein it is

exposed grade silver

silver.

is

also a fissure in andesitic rocks.

known concerning

this vein.

Nova In

Nova

near East

Where

found to carry pyrite, galena and various highminerals in a quart zitic gangue. Very little is

Scotia there are

Bay and

at

Scotia

some

argentiferous galena deposits

Musquodoboit,

which

have been

intermittently worked.

AUSTRALASIA New

South Wales

Most of the silver extracted from ores mined in New South Wales is contained in ores of the silver-lead type, and the Broken Hill mines are by far the largest contributors. A small amount of the metal, however, was obtained from the copper ores raised by the Great Cobar mine.

Only a small fraction of these ores receive metallurgical treatment at works within the confines of the State the major portion of ores and concentrate is either forwarded ;

to oversea countries, or else these have their silver contents extracted in other States of the Commonwealth.

Silver is recorded as having been produced in 1919 at One of these, smelting works in New South Wales.

two the

Electrolytic Refining and Smelting Co., of Australia, Ltd. The other, at Port Kembla, produced 114,081 oz. silver.

that of the Sulphide Corporation, Ltd., at Boolaroo, furnished 1,108,102 oz. silver [34].

Cockle Creek,

AUSTRALASIA The

53

following table gives the productions of silver in

South Wales from 1910 to 1919

New

:

Estimated Quantity and Value of the Silver yielded by the Mines of New South Wales

[34]

Broken Hill Mines. The famous silver-lead-zinc deposits of the Broken Hill district are situated within the Albert district and about 15 miles from Silverton, a town near the western boundary of New South Wales. The lying

mining first

discoveries in the district, namely, of cerargyrite, were made and from 1889 to 1896 the Broken Hill Pro-

in the year 1884,

prietary, Ltd., the most important of the operators, produced over 2,000 tons of silver. By the year 1915 the total output

Company had reached approximately was stated at the 39th ordinary general meeting on June 12, 1919, that the reserves of the Broken

of

silver

by

177,000,000 oz.

this

It

Hill Proprietary Co., Ltd., were estimated in December, 1918, at 1,095,015 tons of ore of an average assay value of 6*7 oz.

and

n-6% zinc. Details concerning the operations of the other companies engaged in the exploitaIn 1918 tion of the metalliferous deposits are given below.

silver,

12-8%

lead,

the ore raised from the mines on the Broken Hill field amounted to 1,251,161 tons. to 415,400 tons.

The

A

serious strike reduced the 1919 output

district consists of

complex

an ancient and highly contorted and mica-, hornblende- and

of gneisses, quartzite

SOURCES OF SUPPLY OF SILVER ORES

54

garnet- schists, into which are intruded dykes of basic diorite. These rocks are covered in greater part by sedimentary deThe ore-bodies are conposits of recent and Pleistocene age.

formably intercalated in the metamorphic complex, and the

The footprincipal deposit is in the form of a saddle. wall is generally sharply denned, but on the hangingwall side, the ore and country rock pass insensibly into one

another.

haematite,

native etc.

The

principal

psilomelane,

silver,

together

oxidized

ores

are

limonite,

rhodonite, cerussite, cerargyrite, kaolinized felspar, garnet,

with

At greater depths

this association passes into sulphide principally of a coarse-grained mixture

ores,

consisting of galena and blende.

In addition one finds quartz, garnet,

felspar and rhodonite, and, more seldom, pyrite, chalcoThe average ore contains pyrite, arsenopyrite and fluorspar. and to to to zinc, 5 38 oz. of silver per ton. 30 5 7 % lead, 14 " with some quartz of kaolin dry ore," consisting High-grade and garnet, contains 4 to nearly 300 oz. silver per ton, whilst

%

"

"

dry ore usually has 5 to 40 oz. silver per ton. No general agreement has been reached on the subject There are typical of the genesis of these ore-deposits. contact minerals present, but these are older than the orelow-grade

deposits.

The

following details of the output of the various companies engaged in the exploitation of the Broken Hill deposits

have been taken from the Annual Report of the Department of Mines, New South Wales, for the years 1917 to 1919 [34] :

AUSTRALASIA

55

of the Broken Hill Proprietary Co., Ltd., to included 176,781,329 oz. fine, of silver 102,857 1915, June and 1,487,640 tons of lead. 1 The total contents oz. gold of the crude ore, bullion and concentrate disposed of up to

The output 2,

;

;

the end ot 1919 by the Broken Hill Proprietary Block 14 Co., Ltd., are estimated at 13,993,907 oz. silver and 255,883 tons In the case of the Broken Hill Proprietary Block 10 lead. Ltd., the crude ore and products (including tailing) disposed of were estimated to contain 38,209,213 oz. silver Co.,

and 393,586 tons

lead.

The output

of the Central

mine since

commencement

of operations by the Sulphide Corporation, end of the year 1919, includes 41,863,181 in to the Ltd., 1897, The concentrate produced by Broken Hill South oz. silver.

the

Likewise, Silver-Mining Co. contained 18,695,921 oz. silver. considerable amounts of silver have been produced by the other

companies not enumerated above. The output of the North Broken Hill, Ltd., for the year 1919 was 53,984 tons milled, which produced 10,890 tons of concentrate of an average assay value of silver, 27-4 oz. to the ton lead, 63-6%; zinc, 7*5%. Cobar Mining Field [35]. Considerable amounts of gold, silver and copper, together with small amounts of lead, have ;

been obtained from the ore-bodies of the Cobar mining district. By far the most important mine is the Great Cobar mine, situated in the parish of Cobar, County Robinson, and 459 miles west by rail from Sydney. The country is composed

and slates probably of Silurian age. The Cobar Lode consists of large lens- shaped impregnations and replacements of the country rock. No true walls exist, as is usual with deposits of this type. The ore is largely made up of pyrrhotite, associated with which are pyrite and chalcopyrite. It is comparatively poor in silica and thus affords a cheap and efficient means of extracting the gold and silver contents of the siliceous ores obtained from the neighbouring Cobar Peak Silver mine. During 1901-2 an electrolytic plant was established at Lithgow for the separation of the gold and silver and the production of electrolytic copper. The following table gives the quantity of silver obtained

of sandstones

1 From information published at time of the disposal of the company's reduction works to the Broken Hill Associated Smelters Proprietary, Ltd.

5

SOURCES OF SUPPLY OF SILVER ORES

56

from the Great Cobar mine, and the mines held in the same interests, during various years from 1898 to 1919. (The mine is

now

closed down.) Oz.

1898 1903 1908 1913 1914

Oz.

145,665 40,4 3 90,196 103,837 24,305

1915 I9l6 1917 I9l8 1919

47, 8l 9 45,206 38,009 8,594

The

quantities of silver obtained in the Cobar mining district for the years 1911 to 1919 are represented by the fol-

lowing figures

:

Oz.

1911 1912 1913 1914 1915

125,276 275,861 125,297 24,612 1,838

Oz.

1916 1917 1918 1919

.

.

47,968 55,923 98,203 18,340

[34]

Yermnderie Field.

A

number

of

mines situated in the

Yerranderie division, which lies within the confines of the Southern Mining District, raise ores of the lead-silver-gold type.

The

Yerranderie

following table shows the outputs of silver of the field for various years from 1900 [34] :

Oz.

1900 1905 1910 1913 1914

58,527 243,403 783,295 475,866 520,880

Oz.

1915 1916 1917 1918 1919

475,180 174,321 276,034 317,459 286,955

During the year 1919 the Colon Peaks mine raised 1,156 tons and 178 oz. and the new ore conof tons gold; Burragorang mine, 769 oz. 62 tons and oz. silver, lead, taining 30,856 44 gold the Tonalli mine 4,466 oz. and Dunn's mine 520 oz. of silver. Other mines producing silver are those of Silver Peak, Silver King and Yerranderie. Other Localities. A few years ago a considerable quantity of silver was obtained from ores raised by the old Conrad mines at Howell, in the Tingha division. In 1912 these of ore containing 110,584 oz. silver, 342 tons lead,

;

;

Peak mine

only.

AUSTRALASIA

57

mines yielded 395,244 oz. silver. In 1919 only 50 tons silver- lead ore, which after treatment gave a return of 3,291 oz. of silver, were raised on a mineral lease which originally formed part of the old Conrad mines. During of

the same year, small amounts of ores containing silver, chiefly of the silver- lead type, were raised in the parish of Op ton, Burrowa division at Carboona, Tumbarumba division in ;

the

;

Condobolin division

;

the divisions of Orange, Drake. During the year

also in

and Corner, Leadville, the silverlead1910 copper deposits of the

Sunny

yielded 133,777 oz silver, and in 1912, 93,088 the output had fallen below 3,000 oz. silver. -

In addition to the above

Kangiara field but in 1919

oz.,

where the occurrences

localities,

are essentially of the silver- lead type, there are a large number of places in New South Wales at which copper ores containing

appreciable amounts of silver have been found.

Queensland

The

produced in Queensland is obtained as a byproduct in the metallurgical treatment of copper, gold, lead and arsenical ores. The bulk of the metal is derived from Thus the Herberton and Mackay copper and gold ores. silver

yield copper and silver; the Cloncurry, Chillagoe, Charters Towers, and Mount Coolon fields, gold and silver the Mount Morgan and Gladstone fields, copper, gold and

fields

;

silver

;

the Etheridge and Cania fields, lead and silver, and

in the Stanthorpe field, ores of copper, lead, gold, silver

arsenic are found together. The table on page 58 gives the production Queensland for the years 1916 to 1919

and

of silver in

:

Here the most important producer is the which in 1918 yielded copper and silver comEmpress mine, Herberton Field.

bined to the value of nearly 10,000. The second largest producer of copper and silver is the Rio Tin to mine, Mount Albion, where the silver content amounts to about 514 oz. per ton of copper and 90 oz. per ton of ore. The proportion of silver at the Richard's Queen mine averages 146 oz. per ton of copper.

SOURCES OF SUPPLY OF SILVER ORES Production of Silver in Queensland, 1916-1919 [36]

1

Including 10,082 from Brisbane district.

Cloncurry Field. This is by far the most important copperproducing centre in the State. Returns of the total mineral

output for the field for 1918 show that 189,219 tons of copper ore were treated at the various smelters on the field, for a f copper, 3,851 oz. of gold, and 19,362 8 tons 3 cwt. of silver ore, treated at the Sulphide Corporation Works, yielded 10,124 oz silver. Stanthorpe Field. Practically the whole of the silver out-

yield of 11,625 tons oz. silver.

Some

-

field comes from the Silver Spur mine, in County In Clive. 1918 this mine produced, besides some gold and copper, 24,239 oz. silver and 21 tons lead. The lode was discovered in 1890, and during the period 1892-1913 a total

put of this

The over 2,000,000 oz. of silver was produced. described is rock as a fine-grained, predominant country of

a

little

slaty mudstone, and an intrusion of diorite occurs in the neighbourhood of the ore- deposits, which are confined to lines of

crush and possess a general lenticular shape. The ore consists of chalcopyrite, blende, pyrite, galena, quartz and calcite. The amount of silver recovered averages 22 oz. per ton of ore [37]. At the

varied

Comet mine the ore consists of arsenopyrite with amounts of galena, chalcopyrite, wolframite and

AUSTRALASIA Two

cassiterite.

samples gave 10

oz.

59

and 28

oz.

of silver

Similar associations of minerals carrying a little silver occur at the Orient and Gibbinbar mines, and in the Gold, silver neighbourhood of Sundown and Ballandean. respectively.

and arsenic are associated

in the

Norton Arsenical Goldfield,

the ore containing about 5 oz. silver per ton [38]. In this district practically the whole of Ether idge Field.

obtained from silver-lead ores. The principal producers of silver-lead ores during the year 1918, arranged in order of importance, are the Queenslander, Aspasia, Percy the silver

is

River Copper Co., Dry Hash, Southern Cross Extended, and Mount Jackson mines.

Here the only important producer

Chillagoe Field.

of gold

and

silver is the Tyrconnell mine, at Kingsborough. During the year 1918 this mine yielded from 3,550 tons of ore raised,

3,725 oz. gold and 1,758 oz. silver. The silver is obtained as a by-product Charters Towers. from gold and other ores.

The Mount Cannindah mine and the mines and gold, whilst the Mircam mine yields copper and silver. Mount Coolon Field. Here small quantities of silver are associated with the gold. The principal workings are at the Gladstone Field.

at Glassford Creek yield copper, silver

Native Bear mines.

Mackay Field. A small quantity of silver was, in 1918, obtained from two copper mines, viz. Mount Flora and Pine Vale.

Cania Field.

[39]

The Mount Prospect

silver-lead lode

situated 4 miles by road south-east from Cania, and 116 miles by rail from the port of Rockhampton. The oxidized galena ores contain about 44% lead and 55 oz. silver per ton.

is

The

ore is principally galena and the lode occurs in granite. In 1918 work was confined to opening up the lode, but in absence of a treatment plant, only the sorted higher grade ore can be marketed. The returns for February 1919 show 171 oz. silver

and one ton

of lead

from 5-7 tons of ore. and lead has been

It is stated that ore containing silver

dis-

covered in the parish of Jondaryan, County Aubigny, Darling Downs [40/p. 117]. Also, a silver-lead deposit is reported

SOURCES OF SUPPLY OF SILVER ORES

6o

as having been discovered on Finney's Twelve tons of ore gave a return of 1,245 of

lead.

In addition

Hill,

Indooroopilly. and 8 tons

oz. silver

J ton of galena gave 138 oz. silver

[40/p.i35].

South Australia

True silver ores do not occur in South Australia, but a small annual output is recorded as a by-product from the smelting of copper and lead ores. The ores of the Wallaroo and Moonta bulk of the production, although small also are obtained from argentiferous galena. The quantities total production of silver from 1910 to 1919 is given as 25,889 district furnish the

oz.,

valued at

and

of silver-lead ore as 1,623 tons valued following table gives various outputs and

3,340,

>

The 28,800. values of silver and silver-lead ores at

from 1907 to 1919

:

Production of Silver and Silver-lead Ores in South Australia

[41]

The following table gives the and Moonta from 1909 to 1916

silver production at

Wallaroo

:

1909 1910 1911 1912

The Silver-Lead Deposits [41]. Taken individually the mines of South Australia have in general yielded but small amounts of silver, and have shown no inclination towards continuous production. Mining operations have This been carried on in a somewhat desultory fashion.

silver-lead

AUSTRALASIA

61

observation applies more particularly to those which have been active at various times during the past ten or twenty years.

The old silver-lead mines of the Glen Osmond group, situated Mount Lofty Ranges, were the first mines to be worked in South Australia Wheal Gawler, opened in 1841, is possibly the oldest mine in Australia but little has been done on these since the early days and nothing at all during the last twentyseven years. Mining operations are conducted on a small from want of capital. Many of the suffered scale, having in the

deposits Most of

do

not appear to have been adequately tested. them occur as fissure-veins, although, at Ediacara,

for example, argentiferous galena occurs disseminated through a gently-inclined bed of crystalline limestone of about 18 inches in thickness. The fissure- veins are generally narrow,

but tend to occur in groups.

The silver-lead lodes are confined to the complex of Cambrian and pre-Cambrian rocks which has an extensive distribution in the southern part of the State, as will be seen in the

Mines

More particularly they Department's geological map [43]. show a disposition to fall within three areas, viz. (a) the district immediately to the south and east of Adelaide (6) the country between Lakes Frome and Torrens and (c] the neighbourhood ;

;

of Olary.

Thus the

Mount Malvern,

Wheal

Coglin, Commonwealth, Oli vaster, Yattagolinga, Talisker mines and

Aclare,

Osmond group would fall within the first district the Avondale and Williams mines belong to the second district and the Commodore, Perseverance, Uncle Tom, and Wincklen's

the Glen

;

;

mines are situated comparatively near Olary. In general, it may be said that the Cambrian and pre-Cambrian rocks which have not so far been differentiated at most points consist of a highly disturbed series of mica-schists, quartzites, crystalline limestones and dolomites, and various types of gneisses, penetrated by a variety of igneous rocks [44] [45].

As already mentioned, the bearing deposits

is

chief constituent of the silver-

argentiferous galena.

The content

in lead

from about 10 to 70%, the average being about 45%. The amount of silver varies considerably, being from 2 to 40 oz. varies

per ton.

SOURCES OF SUPPLY OF SILVER ORES

62

Tasmania

The productions

of silver-lead ores in the whole of

for recent years are as follow

1

Tasmania

:

Oz. silver.

[46]

North Pieman, Huskisson and Sterling Valley District

[47].

This district forms a portion of the west coast mining region and occupies the south-eastern corner of Russell County. The ore deposits can be classified as pyrite

and

galena

:

(a)

silver-lead veins

replacement bodies

;

(c)

;

(6)

galena-blende-

Silver, in chalcopyrite deposits, and (d) chalcopyrite veins. is associated with and amounts, varying galena chalcopyrite. The silver-lead veins consist of galena, blende, pyrite, with

a

arsenopyrite and chalcopyrite. The gangue is quartz. veins are of the tabular-fissure type and occur in sheared

little

The

graphitic slate, near its junction with the porphyry intrusions.

The average width of the lodes is about 4 feet. The district is occupied by the West Coast conglomerate, the Read-Rosebery schists, the Farrell slates and the Dundas slates and breccias, all of pre-Silurian age, in addition to preWithin the Silurian felsites, keratophyre and porphyries. igneous rocks the lodes carry chiefly chalcopyrite, whilst in the sedimentary rocks near the contact, blende, galena and pyrite

predominate. Rosebery District [48].

In the Rosebery district the silver

of the zinc-lead sulphide ore-bodies amounts to about 10 oz. per ton of ore, and is associated with galena and tetrahedrite.

Scamander Mineral District [49]. This district lies on the Tasmania and on the north side of St. Mary's station. It is occupied by Ordovician slates and sandrailway stones intruded during Devonian times by granite and granite east coast of

AUSTRALASIA

63

porphyry. The silver-bearing ores consist of pyrite, arsenopyrite, galena, blende, chalcopyrite and gold in varied amounts, and occur in lodes which occupy the coastal zone, chiefly in

To the west of this zone is another characgranite porphyry. terized by lodes of chalcopyrite and pyrite carrying smaller amounts of silver. The Scamander silver-mines in 1911 were reported as having been abandoned. Zeehan Field [50]. This area is occupied by Palaeozoic sediments, with spilites, tuffs, gabbro-amphibolite, and the granite

Mount Heemskirk which has played an important The ores, which consist of and with various amounts of argentiferous galena pyrite and stannite, occupy siderite blende, chalcopyrite, tetrahedrite, fractures and crush-zones in the Silurian rocks. The simple first discovery of mineral wealth was made in 1882, but serious massif of

part in the genesis of the lodes.

operations were not begun until 1890. During the next few years mining was very activei the most prominent mines being

Zeehan-Montana, Zeehan- Western and Oonah. At 300 to 400 however, the lodes began to be unremunerative, causing most operations to be suspended. In 1898 the works of the feet,

Tasmanian Smelting Company were erected on the ZeehanStrahan Railway, two miles from Zeehan. Gladstone Mineral District [51]. The township of Gladstone lies on the north-eastern corner of the island. The gold of the Tasmanian field at as usual in Tasmania is Gladstone, Royal

when

in close proximity to the granite, is

accompanied by a

considerable proportion of silver. Assays show an irregular of to silver. proportion gold Samples from Fleming's Reef in the new shaft have given as much as 4 oz. silver to 10 oz. gold,

and as

little as I oz. silver to 8 oz. gold per ton. In the Portland district and in the Portland gold mine, four miles north-east of Gladstone, the silver exceeded the gold content two or threefold. This mine is now abandoned. In the slate country north-east of Gladstone and west of the

Great Mussel Roe a group of gold-quartz reefs occur which carry small quantities of gold and silver with arsenopyrite, galena and blende. No work had been done in depth.

Mount

Lyell [35].

Lyell, operated

by

The pyritic copper deposits at Mount Mount Lyell Mining and Railway Co.,

the

SOURCES OF SUPPLY OF SILVER ORES

64 Ltd.,

on the west coast of Tasmania, are richer in

gold than

is

usually the case with the so-called

pyrite deposits."

The

ore-deposits consist of

mineralized bands of schist and

silver

"

and

intrusive

two types

(i)

great lens-shaped masses of Of the latter there are two main (2)

very pure sulphide ores. The average silver content, according to Peters, was estimated at 3 oz. per ton. Actual work has proved that the ore treated up to the end of September 1902, viz. 1,320,131 The 1918 tons, yielded an average of 274 oz. silver per ton. and 1919 outputs were 320,344 and 266,864 oz. respectively. Middlesex and Mount Claude Districts [52]. These districts are situated in the southern part of the county of Devon, which occupies the north central part of Tasmania. Stated in very general terms, the area consists, geologically, of a mass ore-bodies.

Devonian granite, intrusive into Silurian limestone, and preSilurian conglomerates and slates. In addition there are rocks of a felsitic affinity, as well as lavas and tuffs of Tertiary age. of

Lodes carrying argentiferous galena and chalcopyrite occur Round Hill, at Wilmot Valley, near Bell Mount, and at the Thistle, Union and other mines in the vicinity of Lorinna.

at

The

silver content of the lead ores in the district is varied.

A range has been observed from

J

oz. to 10 oz. of silver per unit

by ore verging on tetraThe gold content ranges from a trace up to 25 dwt. per In some of the lodes of the region silver is found in

of lead, the higher ratios being yielded hedrite. ton.

association with wolfram.

The Round Hill mine is owned and operated by the Round and Lead Mining Co. The ore consists dominantly of galena, with abundant chalcopyrite and a little pyrite, blende and siderite as common associates. The following table gives the statistics of the production of the mine from 1907, when operations were first commenced by the present company [53] Hill Silver

:

AUSTRALASIA

65

Victoria

According to the Annual Report of the Secretary for Mines whole of the silver produced since 1900 has been extracted from gold at the Mint in Melbourne. No silver-lead ore has been raised in Victoria since that date.

for 1918 the

The

total amount of silver extracted from gold at the Mint Melbourne up to the end of 1918 was 1,424,299 fine oz., valued at 215,123, and the total amount derived from other sources amounted to 30,577 fine oz., valued at 7,880. The total quantity of silver-lead ore raised to the end of 1918 was 793 tons, valued at 5,760. In the year 1917 it is stated that 7,669 fine oz. of silver, valued at The 1,406, were extracted from gold at the Mint [54].

in

year 1918 produced 6,333 fine oz. (value

1,319).

Western Australia

Apart from the gold and silver tellurides of the Kalgoorlie goldfield, silver minerals have only been recorded on rare occasions in Western Australia. The small annual production of the metal is practically all obtained as a by-product from the metallurgical treatment of gold, and to some extent of copper

Up

ores.

end of 1919 the total value of the silver producamounted to 496,812, which appears particuinsignificant when compared with the total gold proto the

tion in the State larly

duction of

140,729,627. It is stated that the average Kalgoorlie Goldfield [8]. Kalgoorlie ore contains about i oz. of silver for every 2 oz.

of gold.

The

silver is

combined with the

The

gold, or, in rare

weathering have been the complete oxidation of pyrite and other sulphides, and the oxidation of all the tellurides with liberation of free

instances, exists as chloride.

effects of

gold and silver. In the unoxidized ores, gold and silver occur as free native gold carrying a little silver, as pure telluride of gold (calaverite), as pure telluride of silver (hessite), and as tellurides of both gold

and

silver (petzite, sylvanite

and krennerite).

SOURCES OF SUPPLY OF SILVER ORES

66

Silver production of Western Australia, obtained as By-product

and exported

Phillips River

mining district,

district

Mining lies

District

[56].

The

Phillips

River

within the boundaries of the Oldfield

which comprises part of the south-western portion

The

lodes consist of fairly regular bodies of copper ore, carrying small amounts of gold and silver. The of

the State.

country rock

is

chiefly gneissic granite with

some

dioritic

gneisses.

Yilgarn Goldfield [57]. The gold of the Mount Jackson and Greenmount and probably other mining centres in the Yilgarn goldfield, carries small amounts of silver. Thus the total yield of fine silver up to 1908 from the Mount Jackson centre was 2,305 oz., and from the Greenmount centre 664 oz. Kanowna District in N.E. Coolgardie Goldfield [58]. Up

Kanowna mining centre produced a and the Gindalbie 38 oz. silver.

to 1908 the oz. silver,

total of 2,412

Silver-Lead Deposits It is reported [59] that a lode containing silver-lead ore was discovered in the country lying between the Davis and Oak-

over rivers, at a point 90 miles from Marble Bar and 60 miles from Wallwal, on the seaboard. The lode is stated to have been traced for 9 miles. A parcel of about 3 tons of ore

AUSTRALASIA

67

assayed 50% lead, 6-85 oz. silver, and 2*62 valued at about 21 per ton.

New

% copper per

ton,

Zealand

Practically the whole of the output of silver in New Zealand results from the metallurgical treatment of the gold occurring

Waihi-Tairua and Thames goldfields, situated in the Hauraki Peninsula, North Island. Silver ores proper apparently have not been discovered in commercial quantities in New Zealand, although there are several places at which important deposits of silver-bearing lead and copper are stated to occur. in the

*

Quantities

and Values of

Silver exported from for various Years since 1902 [60]

New

Zealand

In the Waihi goldfield the unoxidized ore consists of quartz, manganiferous calcite and mineralized porphyrite, with a varied percentage of pyrite, blende, galena, chalcoThe gold-fineness of the electrum pyrite and argentite. from the ore of the Waihi mine is 0-645. This electrum is found in the veinstones either in a very fine state of subdivision enclosed in the various sulphides, or is sparsely disseminated through the oxidized ore. Tellurides of gold and silver occur in the Silverstream, Old Maratoto, and other mines at Maratoto.

These consist mainly of hessite, with probably some admixture of petzite. Argentite occurs throughout the sulphide ores of Waihi, Golden Cross, Maratoto, Komata and Khargamata. Other minerals are pyrite, with chalcopyrite, galena, blende, rhodochrosite, pyrolusite, etc.

Thames

The Thames

Goldfield [61], 1

Estimated.

goldfield

is

situated

SOURCES OF SUPPLY OF SILVER ORES

68 in the

Hauraki Peninsula, Auckland, North Island.

Through-

occurs alloyed with gold in the form of and also as tellurides. electrum, According to Fraser, it is difficult to estimate the production of silver; probably

out the

field silver

85,000 represents the minimum value of silver produced from the opening of the field, in 1867, to the end of 1908.

Quartz and pyrite are the main gangue minerals of the Sometimes calcite, rhodochrosite, galena, gold-silver veins. blende and chalcopyrite are found in close association with these.

CHAPTER

III

SOURCES OF SUPPLY OF SILVER ORES (b)

continued

FOREIGN COUNTRIES EUROPE AUSTRIA

Styria, to the north of Graz, are argentiferous lodes which contain blende and galena, with sulphides of copper and iron,

IN

quartz and other minerals. The galena carries about 0-06% The country rock consists of calcareous, chloritic

of silver.

and argillaceous slates. At Pfunderrerberg the lodes contain galena and sulphides of copper, iron and zinc. The galena contains 0-3 to 0-6% of silver, while the copper and iron sulphides are auriferous. The district is made up of gneiss and slates traversed by intrusions of diorite, aplite and micropegmatite. CZECHOSLOVAKIA

At Przibram, in Bohemia, is a silver-lead district which includes the towns of Przibram and Birkenberg on the left of the River Moldau, to the south-west of Prague. The country consists of Lower Silurian slates and sandstones,

bank

which about 2 miles to the south-east of Przibram give place to granite and phyllite. These rocks are intruded by numerous dykes and bosses of greenstone, with which the lodes are intimately associated. The lodes are of the lead-silver type, and the principal ore consists of argentiferous galena with blende, siderite and pyrite in a gangue of calcite, dolomite, quartz and barytes. Silver minerals also occur in places.

The

earliest available records of mining operations at Przibram date from the beginning of the sixteenth century. In 1910 69

SOURCES OF SUPPLY OF SILVER ORES

70

the output amounted to 47.7 tons of fine silver, 3,390 tons of soft lead, 596 tons of antimonial lead, 155 tons of zinc ore

and 50-5 tons

of

antimony ore

[lo/p. 705].

According to the Engineering and Mining Journal, the silver production of Bohemia amounted to 1,478,000 oz. for the year 1915, all of which was obtained from the mines at Przibram. To the west and south of Pilsen, in eastern Bohemia, lead and zinc ores occur, with quartz and subordinate amounts of barytes and fluorspar, or calcite and dolomite. The silver content of the galena varies between 0-05 and 0-2%. At Kuttenberg and Budweis, in Bohemia, there occur lodes of galena and blende, with quartz, dolomite, pyrite and sulphide of arsenic. Native silver and red silver ores also

The districts contain gneiss Cretaceous and rocks invaded by granite, pegmaby

occur in subordinate amounts. overlaid tite,

and mica

trap.

FRANCE The Saint Sebastien d' Aigrefeuille Deposit [lo/p. The argentiferous lead deposit of Saint Sebastien

1179].

d' Aigreoccurs near the village of Generarques in the department of Gard. The ore-bearing beds consist of Upper Triassic

feuille

conglomerate and sandstone, some

and fills

n

yards thick, and rest granite, and are overlaid in parts by Lias Dogger. The ore consists of galena and pyrite, which the spaces between the pebbles over large areas of the

directly

upon

The payable masses have very irregular outThe maximum lead content of the ore-bodies is 30 %

conglomerate. lines.

;

their average content 6 to 10%, while the whole bed may contain 2 to 4%. The amount of silver found with the lead is

very varied, but on an average amounts to 58

oz.

per ton of

lead.

In the Auvergne important lead lodes carry argentiferous galena, with sulphides of zinc, iron and copper, and antimonial compounds in a quartz and barytes matrix. These lodes chiefly occur in gneiss and other metamorphic rocks traversed by veins of fine-grained granite and quartz-porphyry, and are

FRANCE GERMANY

71

contemporaneous with the older of the Tertiary volcanics, which are overlaid by later extrusives. In the departments of Cantal, Haute-Loire and Puy-deDome, some of the antimonial lodes carry silver. These lodes occur in gneiss, mica schist and granite. The now abandoned argentiferous galena district of Pontgibaud, in the department

Puy-de-D6me, produced important amounts from 1760 to 1780. of

GERMANY (INCLUDING

of silver chiefly

SILESIA)

Mansfeld District [io/p. 1121]. In the Kupferschiefer (bituminous marl-shale bed) of the Zechstein formation, copper occurs principally as chalcopyrite, chalcocite and In the Mansfeld bornite, and with a varied amount of silver. district the average is 0-55 parts of silver to 100 parts of copper, but in Reichelsdorf and Westphalia, the silver contents only .

about one-fifth and one- twenty- fifth of the above Very little silver exists in Thuringia, where respectively.

amount

to

the silver

is

associated with pyrite as well as with copper. in the Mansfeld district,

Between Gerbstadt and Eisleben, the Kupferschiefer contains 2 to of silver per ton of copper. Freiberg District (Saxony).

1163 to 1896

is

given as follows

3%

The

of copper total

and 180

oz.

from

production

:

Oz.

1163-1523 1524-1835 1836-1896

The formation

.....

63,171,300 56,598,201 49,315,861

consists of granite-gneiss surrounded by a mica schists and other metamorphosed

contact- aureole of

Quartz- silver lodes occur containing argentite, pyrargyrite, proustite, etc., and silver- lead lodes with dolomite or with barytes. The silver seems to have been associated sediments.

with the grey gneiss, and lodes become poorer on entering red gneiss or mica schist. Altenberg District (Saxony).

Bergmannstrost,

which

blende, tetrahedrite, etc. 6

The

carries

best- known

arsenopyrite

lode

with

is

the

galena,

SOURCES OF SUPPLY OF SILVER ORES

72

Other lodes

may

be described as gold-silver lodes, and

contain copper minerals as well. The Bergmannstrost and Liischwitzgrund lodes contain traces of gold only, and 5

and ij

oz. of silver per ton respectively, whilst the MariaForderung, Olgar-Wunsch and Wender-Hoffnung lodes contain 10, 2 and 17 dwt. of gold, and 6, 2 and 7 oz. of silver per ton respectively (Beyschlag and Vogt).

The formation

consists of dark-coloured slates (probably Silurian), with intercalated porphyry and diabase, and some small intrusions of porphyry and olivine-kersantite.

This region includes the disSchneeberg, Johanngeorgenstadt, Annaberg, Marienberg and Scheibenberg-Oberwiesenthal. Silver only occurs to a limited extent in Schneeberg with cobalt-bismuth

Upper Erzgebirge (Saxony).

tricts of

ores.

At Johanngeorgenstadt

silver- bearing

lodes contain

ores of bismuth (principally), cobalt and uranium. The other Ores districts were renowned for their cobalt- silver ores. of tin, copper, lead, zinc and iron were also mined. Clausthal District (Harz Mountains). The formation of the

n

Clausthal plateau,

miles long and 5 miles wide, chiefly beds. The silver-lead lodes

Culm and Devonian

consists of

are fault-fissures of considerable width, the hanging- wall being disturbed and undefined. The principal ore is galena carrying

%

of silver. Blende is common, whilst chalcopyrite, O'Oi to 0-3 tetrahedrite and bournonite also occur. Quartz is the pre-

In 1908 vailing gangue. tons of argentiferous galena

eight mines produced 265,000 and blende, valued at 202,000 at

the mine.

The copper and mixed ores of the pyrite deposit at Rammelsberg, on the N.W. border of the Harz, contain 0-015% of silver.

Andreasberg District (Harz Mountains). The ore-bodies the silver-lead-zinc lodes were discovered in 1521, and reached a maximum of prosperity during the latter half of the St.

of

then followed a period of quiescence, but were resumed about the middle of the mining operations seventeenth century, and continued until 1910, when the ore-

sixteenth century

become exhausted. The lodes, rich galena, blende, and ores of silver, arsenic, etc.

bodies had carried

;

in

silver,

GERMANY Tarnowitz-Beuthen District

(Silesia).

73

The metasomatic silver-

lead-zinc deposits of this district occur interbedded in Muschelkalk limestone (Triassic), and contain galena, with from

0-048% of silver, blende, zinc carbonate, zinc Mining began in the sixteenth hydrosilicate and marcasite. In 1897 the production in Upper Silesia amounted century. 0*025

to

to 510,686 tons of zinc ore, 35,847 tons 268,400 oz. of silver.

Goldberg District

(Silesia).

of

lead ore

This was once an

and

important

The

to 1883, cupriferous Zechstein, from 1866 of tons of silver. with some oz. ore, produced 58,000 110,500 district.

Berg District (Rhine Province). Numerous argentiferous lead-zinc lodes occur in Devonian rocks. The Luderich lode can be followed for a distance of 2j miles. The ore consists chiefly of compact, fine to coarse-grained galena, carrying from 6 to 16 oz. silver, and sometimes as much as 225 oz. per ton. Blende, carrying cadmium, is abundant, and there are small amounts of chalcopyrite, pyrite and siderite in most places.

Hokappel District (Wiesbaden). The formation consists of Devonian rocks considerably altered by a variety of tectonic disturbances.

The lode-system appears

to be a

strike-fault consisting of a main lode, three transverse lode. The principal contents

composite branch lodes and a are

argentiferous

galena with an average of 2 oz. of silver per ton, blende, siderite and chalcopyrite, with quartz as the chief gangue. The silver content amounts to 0-15% in the compact and fine-grained varieties. From 1905 to 1910 the silver in the lead ore varied from

2 to 2j oz. per ton.

Ems

District

Devonian. blende,

(Wiesbaden). -The

formation

is

Lower

The

ore consists mainly of argentiferous galena, and chalcopyrite, with quartz as the siderite

In the main lode at Friedrichssegen, galena principal gangue. and blende are present in roughly equal proportions. The silver content of the clean galena (65% lead) is about 16 oz. per ton. of

Ramsbech District (Westphalia). The formation consists Devonian rocks, with numerous narrow but persistent

SOURCES OF SUPPLY OF SILVER ORES

74

Galena, with from 0-027 to 0-065%

silver-lead-zinc lodes.

and blende are the chalcopyrite and siderite also silver,

Munsterthal (Black Forest). porphyritic dykes

principal occur. The

The

in biotite gneiss,

galena, with some pyrite,

The gangue siderite and barytes. ores.

constituents.

silver,

consists

Schapbach District. bismuth and other ores

The in a

of

Pyrite,

is

quartz. lodes are associated with

and contain blende and antimonial and arsenical

quartz,

lodes

gangue

f

fluorspar,

contain

galena,

gangue of quartz, barytes,

calicte,

copper, fluorspar,

calcite, etc.

GREECE Laurion District [lo/p. 746]. In the Laurion or Ergastiria the extreme south-eastern corner of Attica, metasomatic silver-lead-zinc deposits occur in crystalline limestone (Upper Marble) and dolomite and calcareous schists (Lower Marble). Between the Upper and Lower Marble there is a bed of mica schist (the Kaesariani mica schist) which has district, situated in

played an important part in determining the position of the These deposits are of an irregular deposits. bed-like form and consist of argentiferous galena, blende

metalliferous

and oxidized ores of zinc. According to von Ernst, the galena, which is usually very compact, has a high percentage of lead and is rich in silver, 60 oz. per ton often being obtained. It is

stated that the slags forming part of the dumps resulting activities in ancient times, contain

from mining and smelting 13 to

14%

1912

the

lead with 16 to 100 oz. of silver per ton of lead. Laurium Mines Co. produced 10,253 tons

In f

argentiferous lead. The islands of Milos, Pharos, Santorin, etc., in the Grecian archipelago, contain argentiferous lead deposits.

HUNGARY The Hungarian

[IO/P. 535]

silver production is derived from gold-silver which are geographically as well as genetically closely associated with a series of Lower and Middle Miocene eruptives. The most important mining districts are those of Schemnitz-

lodes,

HUNGARY

75

Kremnitz, Nagybanya-Felsobanya-Kapnik, and the Transylvanian Erzgebirge. In 1907 the various silver-mining districts contributed the following amounts of silver to the Hungarian production

Schemnitz, 146,447 oz.

:

Nagybanya, 55,212

oz.

;

Kremnitz, 2,515

;

oz.

Felsobanya, 59,888

;

oz.

;

Kapnik,

Transylvania, including Nagyag, 6,289 oz. 53,245 oz. Schemnitz and Kremnitz. At Schemnitz, mining operations date back to some time prior to the year 750. About the ;

year 1600 there were more than 400 mines in operation. However, since the fall in the price of silver in 1900 they have been worked at a considerable loss, the average yearly loss during the period 1903-1907 having been 'about 46,000.

The

contains Triassic

district

Eocene nummulitic beds,

a

limestones

series

and

quartzites,

Miocene lava flows, and a post-mineralization of

chiefly andesites, intrusive diorites, By far the greater number of eruption of Pliocene basalt. In the adjacent sedimentary the lodes are found in andesite.

strata they quickly split up and disappear. Propylitization and alteration of the other rocks have generally

of the andesite

occurred in the immediate neighbourhood of the ore-bodies.

The most important minerals

are argentite, stephanite, galena,

polybasite, pyrargyrite, proustite, tetrahedrite,

etc.

Quartz

the most important gangue mineral, but calcite and other carbonates are also found.

is

At Kremnitz the lodes

Among

likewise occur in propylitized andesite. pyrite and stibnite are common,

the ore-minerals

Quartz is the principal gangue-mineral. Nagybanya, Felsobanya and Kapnik. Felsobanya lies about 5 J miles, and Kapnik about 21 miles to the east of Nagybanya, a town near the north-western border of Transylvania. At while galena

is rare.

Nagybanya the

lodes consist chiefly of auriferous quartz with

At Felsobanya minerals, particularly pyrargyrite. silver-lead lodes carrying some gold occur, whilst at Kapnik the lodes are of the silver-lead-zinc type and contain comparasilver

tively little gold.

Transylvanian Erzgebirge. An area on the north side of the River Maros, in western Transylvania, includes such important

gold-

and

silver-producing

localities

Offenbanya, Verespatak, Zalatna and Ruda.

as

Nagyag,

It consists of

SOURCES OF SUPPLY OF SILVER ORES

76

With the last Jurassic, Cretaceous and Tertiary sediments. are associated Tertiary igneous rocks, chiefly andesite and dacite, and to a less extent rhyolite, forming a number of small detached occurrences. part to

lie

The

lodes are found for the

within andesite and dacite.

The native

most gold,

which generally contains a relatively high proportion of silver, is accompanied by pyrargyrite, proustite, stephanite, native silver, pyrite, galena, tetrahedrite, arsenopyrite, etc. Quartz is the predominant gangue-mineral, although calcite is often abundant, and the frequent occurrence of manganese minerals is

characteristic.

ITALY AND SARDINIA Sardinia

The

Iglesias District [lo/p. 749].

In the Iglesias

south-western Sardinia are extensive argenmining tiferous galena and blende deposits of metasomatic origin. By far the greater number of these lie within Silurian limedistrict in

stones

and appear to be

genetically connected with certain

granitic intrusions partly exposed within the area under The most productive localities, as far as galena consideration.

concerned, are those of Montevecchio, San Giovanni, San Benedetto, Malacalzetta, Nebida and Monteponi. The lode-

is

Montevecchio includes three argentiferous galena At San In depth, blende becomes more common. localities and the other mentioned Giovanni above, galena, often rich in silver, is also mined. During 1889 these deposits

series

at

lodes.

yielded a total output of galena amounting to 25,910 tons, which 12,100 tons was contributed by the Montevecchio It is interesting to note that the more irregular deposits lodes. of

carry most silver, and that the silver content decreases in depth, whilst the amount of blende increases.

In Sardinia, silver ores proper were first discovered in 1870 Monte Narba mine on the eastern coast of the island, where the metal occurs native, as sulphide and as chloride. at the

mines of Monte Narba, Giovanni, At Monte Narba the Bonu, Bacu Arrodas and Correboi. Silver ores occur at the

lode traverses Silurian slate in the vicinity of porphyry [12]. In Tuscany lodes containing argentiferous galena, Italy.

ITALY AND SARDINIA

NORWAY

77

sulphides of zinc, iron and copper in a gangue of quartz and A well-known deposit is calcite, occur in Palaeozoic slates.

the Bottino mine, near Florence.

NORWAY Kongsberg District [lo/p. 660].

some 50 miles west

The

silver lodes at

Kongsberg,

an area about 20 miles long and 3 to 6 miles wide. The area is occupied by a pre-Cambrian complex of gneisses and schists, and the very numerous lodes vary in thickness from that of paper to Often several parallel veins are bunched together. Their 4 in. of Christiania, are distributed over

mostly at right angles to that of the crystalline schists. most important constituents of these veins are By native silver and calcite, although argentite, fluorspar and quartz are to be met with in much smaller amounts. It has long been observed that the silver is almost exclusively confined to those parts of the veins which intercept portions of the schists impregnated with iron and copper sulphides the

strike is

far the

The two principal mining areas are Overberget and Unterberget. Since 1622, when the silver was discovered, some 150 mines have at different times been worked. Most

fahlbands.

of the mines belong to the State. From 1624 to 1815 the output amounted to 18,042,000 oz. of silver, and from 1816 to

1909,

13,548,000 oz.

The net

from 1830 to 1890 was

profit received by the State i-i million sterling. Since the drop

silver in 1892-1893, the production has practiThe production is now very covered the cost. cally only

in price of small.

Near Vefsen, Helgeland, argentiferous lead lodes occur in and older Palaeozoic rocks, which are intruded by gabbro and soda-granite. The principal ore is galena, gneiss, schist

containing 0-2 to

0-8%

of silver.

In addition, the sulphides

of zinc, iron, copper and antimony are found. At Dalane, in Kvitseid, situated in the Telemarken district

of

South Norway, an impregnation of native copper with silver occurs. Telemarken contains Late Archaean

native

conglomerates and quartzites intruded by later preSilurian granite. The Norwegian pyrite occurrences are

slates,

SOURCES OF SUPPLY OF SILVER ORES

78

widely distributed over the country, and at several points contain notable amounts of silver. At Sulitjelma, in Nordland,

where the most important deposit

is

copper contains 0-0448% of silver.

situated, the

The

Bessemer

Rows

deposits at

and at Meraker show similar proportions.

PORTUGAL The most important

lead- mining area in Portugal

of Mertola, near the Guadiana. district is said to contain

24

The galena occurring

oz. silver to the

ton

is

that

in this

[12].

SPAIN Cartagena and Mazarron Districts [lo/p. 547].

bourhood

of

In the neigh-

Mazarron and Cartagena, situated on the Medi-

terranean coast of south-eastern Spain, there are lodes carrying argentiferous galena. At both localities the ore-bodies are

found in close association with Tertiary extrusions of andesite and dacite. At Mazarron the lodes occur within an area about 8 km. long and 3 km. wide, partly in dacite and partly in the

metamorphic series. The principal ores are The gangue consists galena, blende, pyrite and marcasite. of siderite, calcite, dolomite, some barytes and quartz. surrounding

The galena

generally carries 48 oz. of silver per ton, and, exIn 1904, the mines at ceptionally, as much as 95 to 190 oz. Mazarron produced more than 30,000 tons of lead ore with

The mineralized district around Cartagena of lead. has a length of about 10 km. and a width of about 5 km. The lodes, which traverse propylitized andesite as well as the

58%

adjacent sediments, carry chiefly galena, containing on an average 32 to 48 oz. of silver per ton, together with blende, copper sulphides and pyrite. In 1904 the production at

Cartagena amounted to 80,000 tons of lead ore alone. Linares District [lo/p. 709]. This important argentiferous lead district lies on the northern side of the town of Linares, Within this area which is about 260 km. south of Madrid. are several exposures of granite surrounded by Cambrian and The principal country rock is granite Silurian sediments.

and the ore-deposits are most numerous

in the Linares granite

SPAIN

Others occur in the granite mass at La Carolina and at still others in a similar intrusion at Arquillos.

mass. St.

79

Elena, and

The most important 6 oz. silver per ton. present.

mine

Quartz

is

is galena, which contains on an average Blende, pyrite and chalcopyrite are also the principal gangue. The most important

ore

that of Arrayanes, near Linares. Here the galena carries up to about 3 oz. per ton. The lodes at La Carolina

and

is

Elena contain galena which has a silver content of 20 to 30 oz. per ton. This district reached its zenith in 1889 with an output of 118,325 tons of lead. In 1909 the proSt.

duction was 78,848 tons.

At Ciudad 0'4 to

0-5%

Real, 96

km. north of Linares, the lead contains

of silver.

Guadalajara. The silver-bearing veins of Hiendelaencina have been described by Vicente Kindelan [62]. The most

important veins belong to the oldest system, striking E.-W.

The silver ores include native silver, argentite, stephanite and ruby silver. Galena, blende, bournonite, pyrite and are only accidentally present. The gangue of the chalcopyrite richest veins consists of barytes and hyaline or amorphous quartz, or quartz in a state of agate. The formation is gneiss and mica schist. A barren zone occurs from a depth of from 200 to 300 metres, but is succeeded by a rich zone which has been followed to a depth of 600 metres, which appears to be the limit of payable silver ore in that region. The Segunda Santa Cecilia veins from 1904 to 1907, inclusive, produced 787,600 oz. of silver from the lower rich zone. From 1844 to 1870, 9,649,800 oz. of silver were extracted from the Rico lode alone, and since that date the silver output from Hiendelaencina has been almost exclusively from that lode. In Andalusia argentiferous lead and copper ores are accompanied by barytes, strontianite and siderite. Secondary of silver are found in the upper parts of the lodes. In Seville native silver and silver ores are associated with

ores

cobalt ores and siderite. The famous pyrite deposits of the Huelva or Rio Tinto district, in southern Spain, usually contain about i oz. of silver per ton, representing a relation of 1,000 to 1,200 of copper to i of silver.

SOURCES OF SUPPLY OF SILVER ORES

8o

SWEDEN In the Ammeberg district in Orebro, situated about 100 miles Stockholm, blende with some argentiferous in the form of beds and fahlbands. The occurs galena

south-west of

country rock

Archaean granulite, associated with which are

is

and various igneous intrusives. The ore microcline, some quartz, subordinate plagioclase and biotite, and more rarely, pyroxene, hornblende and garnet. The principal ore-bed may be followed almost without interruption for a distance of 3 miles. Of this, however, only a number of lenticular swellings, which in places may reach 12 to 15 m. in thickness, are payable. The deposit

gneisses, limestone is

intergrown

with

probably be regarded as of the contact-metamorphic From 1857 up to and including 1909, altogether 1,968,729 tons of picked and of milling ore were produced. The lead ore contains about 72% of lead and 26 oz. of silver per ton [lo/p. 677].

may

type.

At Sola, which lies about 60 miles north-west of Stockholm, there occurs a metasomatic silver-lead deposit in dolomite, which, however, is now practically exhausted. Mining began in the year 1500 and reached its zenith in the first half of the sixteenth century. From 1510 to 1600, some 200 tons of silver were obtained

1701 to 1800,

;

37 tons;

from 1601 to 1700, 63 tons from and from 1801 to 1908, 87 tons ;

[lo/p. 771].

At Fahlun large quantities of copper have been obtained, but the production latterly has considerably declined. The " soft ore/' consisting of pyrite with chalcopyrite, quartz, contains about J oz. of silver per ton. present in the pyrite deposits of Atvidaberg. etc.,

Silver

was

also

ASIA ASIA MINOR

The

following

data

concerning

the

silver-lead

deposits

Minor have been derived from an written by Penzer in August, 1919 [63]. The chief mines in western Asia Minor which yield

of western Asia

article

silver-

ASIA MINOR

81

lead are those of Balia-Karaidin in Brusa, and Bulgar-Maden in Konia. The mines of Balia-Karaidin date from very ancient

In 1901 there were about 1,600 men employed, and the production was 7,000 tons of argentiferous galena, containing 70% of lead and 0-125% of silver, as well as blende times.

and calamine. In 1910 the output was 12,000 tons of lead and 3,000 to 4,000 tons of blende. In 1913 the output amounted to 13,076 tons of lead and 5,000 tons of zinc ore. The mines are furnished with a modern smelting and refining plant.

The Bulgar-Maden mines, situated a few miles south of the Konia- Adana line in the vilayet of Konia, have been worked by the peasants for nearly eighty years, in a primitive fashion. The deposits occur in the neighbourhood of the contact between micro-granulities and Palaeozoic limestones. Two separate zones have been noticed extending all along the metalliferous formation from Bulgar-Maden to Kizil Tepeh. The annual yield is about 103,000 oz. of silver, 225 oz. of gold and about 400 tons lead. In 1892 the ore extraction was 20,000 tons, containing

20%

of lead

and 209,000

oz. of silver,

and 19 to 26 dwt. increased just

of gold to a ton of lead. These figures before the war, and the mines yielded ore

containing 75% of lead and from ij to 3|% of silver. In the vilayet of Aidin, silver-lead mines occur in Balia,

which from 1911 to 1913 yielded an average of 14,000 tons of lead.

In Angora, silver-bearing lead ore

Maden, Denek-Maden and Elma-Dagh State-controlled,

but the

is ;

found at Ak-Daghall these mines are

last-named was abandoned

many

years ago.

In Castamouni, the argentiferous lead mine at Kurre has been abandoned owing to insufficient means of transport and communication. In Adana, besides the silver-lead mines of Bulgar-Maden, are those of Karalar and Hadjin, while silver, lead and zinc occur at lotape. There are probably other deposits in the northern part of the vilayet, but owing to the lack of communications and transport, no exploitation has been carried on. Recent reports have been received of two lead mines (prob-

SOURCES OF SUPPLY OF SILVER ORES

82

ably

One

argentiferous) 24 miles north-east of Bulgar-Maden. at Delik Tash, 15 miles due east of Bereketli Maden,

is

and the other 9 miles north-west

of Delik Tash.

Silver-lead mines also occur at

Kebah Maden.

It is reported that in 1916 the Germans obtained seventy concessions for the workings of silver-lead mines in Asia

Minor, probably in Brusa and Aidin. Edwards states [64] that most of the lead mines in the

Ottoman Empire contain appreciable amounts of and have been considerably exploited at shallow depths

(former) silver,

by the

ancients.

Before

the war, an

company, the Asia Minor and producing ore per year, and important mines were

was working

English

silver ores at Lidshisi,

Mining about 3,000 tons of being opened on the Kessendere peninsula [i2/p. 558]. Lead and silver, with a little gold, are also mined by the State at Bulgardegh, where about 48,000 oz. of silver are produced annually [i2/p. 558]. Co.,

CHINA In Chi-li and North Shansi (North China) silver is obtained from deposits of argentiferous galena. At Ten Yung Shang, in the Je-hol district of Mongolia, a vein occurs in limestone

near the contact with metamorphic schists. It is worked by the Chinese. The vein strikes E.-W. and dips N.5o-7O.

The galena

carries

300

to

500 oz. of silver per ton, and

In the Qu-San-Tzu blende, also present, 12 to 18 oz. per ton. mines, seven miles east of the last, galena with tetrahedrite carries 100 oz. of silver per ton, and occurs in a vein with the same strike and dip and in a similar formation [i2/p. 618].

In Sze-Chuan

(one of the south-western provinces) the Maha gold mine is said to carry a considerable amount of silver. At Loku-Te-Tye are veins bearing free gold and lead ores high in silver (300 oz. per ton). At Ma-Ta-Sa is a vein of

which is said to produce 122 oz. per ton, and another vein bears argent it e. At Ta-Chien-Lu are the Government silver mines producing 75 to 90 oz. of silver per ton. The vein is 4 feet wide and is worked along its strike for over silver-lead,

CHINA 10 miles.

and

silver

83

This vein contains complex ore carrying copper, lead, but it is only worked for its silver content.

Near Yer-She are veins of gold, silver and copper ore, and in the south-eastern district are veins carrying silver-lead. At Fukea are numerous veins containing copper and silver These mines supplied the greater part of the silver used Tang dynasty. Near Hui-Le-Chao are numerous veins of gold, copper and silver ores, which are worked extenIn the Yen- Yuan district are veins sively by the aborigines. ore.

the

in

carrying gold, silver, lead, copper, zinc and also mercury [65]. In the Hunan province, Central China, is the Shui-Ko-

Shan

zinc and lead mine. The country is limestone (probably Carboniferous) overlaid by red sandstones and shales of Cretaceous or Tertiary age. Large irregular- shaped bodies of ore, composed of blende and galena with pyrite and chalcopyrite, are developed in the limestone at and near its contact with syenite. The latter has small crystals of chalcopyrite disseminated through it. The deposit was the direct result

metasomatic action of the mineral-bearing solutions Lead concentrate contains emanating from the magma. from 9 to 38 oz., and zinc concentrate from 2-5 to 15 oz. of of the

The only other deposit with an imporKungshan in Tungchwan (Yunnan where the principal ores are carbonates. The pro-

silver per ton [66].

tant output province),

is

that of

duction from the Wei-hung-chow

district,

Kweichow,

is

chiefly

silver.

The amount of silver produced in China in 1914 was significant, and probably did not exceed 50,000 oz. [67]. For 1917 the production is given as 63,900 1918 as 70,000 oz. (U.S. Bureau of the Mint).

oz.,

and that

in-

of

DUTCH EAST INDIES Borneo

A

vein

near

Budok, Dutch Borneo, contains sylvanite and silver).

(a telluride of gold

In the Kahajang mine, of the central auriferous district of Dutch Borneo, there is some silver in the ore [69].

SOURCES OF SUPPLY OF SILVER ORES

84

Celebes

The sulphide gold ores at Palehleh, on the north coast, contain 12 oz. of silver per ton [69]. Sumatra In the Redjang-Lebong lodes the ratio of silver to gold to i. In 1906 and

in the bullion is often as high as 10

1907, the

mine produced 248,240 and 327,584

oz.

of silver

respectively [69].

In Western Sumatra, from Tjalang to a point on the coast opposite the island of Poolo Raja, garnet and wollastonite lenses occur in ancient schist, which carry copper (as bornite), silver being by far the chief gold, silver and some platinum product

[70].

JAPAN Silver-mining in Japan dates from a very early period, the oldest records referring to the discovery of silver ore in the From then island of Tsushima, in the year A.D. 674. until the year 1896 many deposits were opened up, but

during the course of the next few years a number of these had to be abandoned on account of the fall in the price of silver.

The production

of the metal gradually increased

from 1874

to 1895, but from 1895 to 1904 remained nearly stationary, in spite of the rapid progress made by the gold and copper

In 1905 there was a considerable increase in the production owing to the conspicuous development of the Kosaka mine and the general increase of the silver production The great increase in 1908 in the gold and copper mines. was due to the development of the Tsubaki mine, and the

industries.

total output for that year was more than 17 times the output in 1875, and 2j times that in 1900. Generally speaking, the ores proper is desilver from of extracted silver production

maintained or increased by the increasing amounts of the metal obtained as a by-product in the treatment of gold and copper ores [71] [72] [73]. clining,

but the total output

is

JAPAN 1880

Production of Silver in Japan,

(U.S.

Bureau

to

1919

of Mint.)

Production of Silver by the Principal Japanese Mines in 1919

[68]

The production of the twenty most important mines during the five years prior to 1908 aggregated 85-2% of the total The greater part of the silver produced by these output. mines came from argentiferous lead ore 18-6% from normal or dry silver ore, and 157% from argentiferous copper ore. It is to be noted, however, that there is a tendency for the output of silver from copper ores to surpass that derived from dry silver ore. The silver deposits, whether in the form of veins, impregnations, or metasomatic replacements, are practically confined ;

to Tertiary volcanic flows of liparite and andesite of the same age. On the other hand, the

and

tuffs

economically un-

important contact-metamorphic deposits are restricted to the region occupied by pre-Tertiary rocks. Several of the principal mines exploit dry silver ore as well as argentiferous lead and copper ores, which occur as lodes

SOURCES OF SUPPLY OF SILVER ORES

86

traversing eruptive and sedimentary rocks of Tertiary age. Of considerably less importance are argentiferous lead and copper ores which occur as impregnations in Tertiary rocks.

With regard

to deposits of the metasomatic type it is stated that, although great numbers of such deposits exist, the only The one actually explored is the so-called Kuroko deposit.

Kuroko deposit was worked in conjunction with the Tsubaki mine, which in 1908 yielded the greatest output of silver of any mine

in Japan. of deposits of the

Numbers

contact-metamorphic type are a are few but known, important, such as those at Kamioka only and Hiragane in Hida. These occurrences are very commonly situated at or near the contact between igneous intrusions and Palaeozoic or pre-Cambrian strata. The Tsubaki mine, opened in 1889,

no longer produces.

The

The country rock consists of Tertiary shales and andesites. " " " kuromono or black ore," a mixture ore is the so-called of argentite, blende,

galena,

pyrites,

chalcopyrite,

barytes,

quartz and calcite. It contains generally 0-07% of silver, but the richer parts yield 0-15% to 0-3% of the metal. The Kosaka

and is one of the most important in Japan. The ore is of the kuromono type and yields copper, silver and gold, and occurs as a large mass in Tertiary tuff The Ikuno mines are said to near its contact with dacite. have been started in 807, although it was not until 1542 that they were worked on anything like a large scale. There are two principal mines, namely the Tasei and the Kanagase, which yield copper, silver and gold. The country consists of Tertiary tuffs, liparite and associated rocks, and the ore is made up of argentite, native gold and silver, with chalcopyrite, pyrite, galena, blende, pyrargyrite, stibnite, quartz, calcite and These minerals occur in a series of veins. rhodochrosite. The Kamioka deposit is said to have been discovered about 1,200 years ago, and yields silver, copper and lead. The rocks are hornblende gneiss with limestone and intrusive quartzporphyry, and the deposits, which consist of argentiferous mine was opened

in 1866,

galena, chalcopyrite, blende, actinolite, epidote, with calcite, quartz, pyrite, etc., occur as lodes.

NORTH AMERICA

SIBERIA

87

SIBERIA

The silver-lead mines of Western Altai, Government of Tomsk, were important in the early part of the nineteenth In Central Altai the deposits lie for the most part and occur as lodes carrying silvera large proportion of barytes. lead ores mixed with bearing

century.

in Carboniferous limestone

mentioned as occurring in these to depths of 700 deposits. and did not feet, operations apparently pay in depth. The in the Salair Mountains are very similar in their deposits Silver

tellurides

are

also

The mines have been worked out

mineral contents, as likewise are those in the Kolybane district, but are stated to be much richer. The Zmeeff mine near

Kolyban Lake, south of Barmaoul, exploited a particularly Another rich group of mines is the Rydirsk

rich shoot of ore.

group

[74].

In 1845 the silver production of 26,331 oz. [74] and in 1891 as 313,462

the

Altai

is

given

as

oz. [12].

NORTH AMERICA The primary silver deposits of the American continents have been formed during, or shortly after, certain epochs of igneous activity, either of the intrusive or of the volcanic type. They are thus intimately connected with occurrences of igneous rock,

and

in general are

found either within such rocks, or at

their contact with the intruded sediments, or within sedimentary The American strata not far removed from the intrusive rocks.

date from two widely separated ages. The period belongs to the pre-Cambrian or early Palaeozoic the second period belongs to the late Mesozoic and the Kainozoic. The older silver and gold deposits of the first-named type silver deposits first

;

occur at various points in the wide stretches of the two landmasses on the eastern side of the American Cordillera. In North America silver is obtained from the copper deposits of the Lake Superior region, but a much larger amount is yielded Considering the vast by the Cobalt district in Ontario. extent of the eastern lowlands in North America it is extraordinary how localized and highly concentrated these deposits are.

SOURCES OF SUPPLY OF SILVER ORES In South America the region east of the Andes is geologically very similar to the corresponding region in the northern part of the continent, but here the silver production is insignificant.

The younger deposits, belonging to the second period, were formed during the great igneous activity which accompanied the building of the Cordilleras, and are thus confined to the western or Cordilleran part of the continents where deposits of the first period are either rare or else concealed by newer sediments or igneous flows. From Cape Horn to Alaska these younger silver deposits occur under similar geological conditions, and were formed during a period dating from Cretaceous times.

Throughout the interior part of region of North America are numberless intrusions of granitic or dioritic rocks and porphyries of later earliest

the

Cordilleran

Mesozoic or Tertiary age. Aureoles of silver-bearing veins surround these intrusions. Contact-met amorphic deposits have been commonly formed where the intruded rock is limestone.

In

Mexico there

intrusive masses of diorite or

are

countless, though small, in Cretaceous lime-

porphyry

around which argentiferous veins or contact-metamorphic In addition to this type of silver deposits have formed. there is another which deposit comprises ore-bodies occurring in lava flows. These include such celebrated deposits as those

stone,

at Comstock, Tonopah and Cripple Creek. They are best in Utah and Colorado. Few Nevada, Arizona, represented of Canadian of these are found north the boundary, and none of them along the main Canadian or American coast. In Mexico the most celebrated silver occurrences belong to the same type. In South America the most prominent formations

Andes are the Cretaceous sediments. During Jurassic and Cretaceous times there was considerable volcanic activity,

of the

unattended, however, by mineralization. In this respect is a difference from North America, where mineralization

there

connected with large plutonic intrusions of the same age. In the Cordilleran region of South America the principal and almost the only period of mineralization seems to be that of the early Tertiary, when igneous intrusions occurred on a

is

Of less importance are ore-bodies associated scale. with late Tertiary lava flows. The poverty of the eastern

large

GUATEMALA HONDURAS front ranges of the

Andes

is

paralleled

89

by the lack

of precious

metal deposits in the eastern or Rocky Mountain range of Canada.

GUATEMALA According to Rene Guerin [75], blende and argentiferous galena abound in limestone in the department of Chiquimula, sometimes being associated with copper carbonate. The ore

on an average contains from 64 to 96 oz. of silver per ton. Silver was formerly coined from the mines of Alotepique to the value The San Pantaleon mine, worked by an of 60,000,000 pesos. English company from 1854 to 1868, produced silver to the value of 44,000,000 pesos.

HONDURAS The republic of Honduras is the largest silver-producer in Central America. The greater part of the production comes from the gold-silver mine of Rosario, near Tegucigalpa, where " " the lodes are connected with rhyolitic intrusions traversing Triassic sandstones and limestones.

The

following account of the silver-mining in

Honduras

is

based on information supplied by Thacer in a paper published in 1891 [76]. The Opoteca mine is perhaps the most important in Hon-

The

ore is free-milling and carries native silver and in addition to gold. The deposit has been extenargentite in The the worked past. assay value of the ore is given sively as about $20 silver and $i gold per ton of 2,000 Ib. An oreduras.

body consisting mainly of argentiferous galena, with blende and pyrite in small amounts, is situated about 3 km. from the town of Valle de Angeles and 32 km. from Tegucigalpa, and The assay is worked by the Animas and California companies. value of the ore is given as about $60 of silver and 30% lead. Silver- and gold-bearing quartz veins, some i to 4-5 metres in width, occur about 3 km. from the village of San Juancito, near Tegucigalpa. The foot-wall consists mainly of " volcanic greenstone," and the hanging- wall chiefly of siliceous slates.

SOURCES OF SUPPLY OF SILVER ORES

90

The Yuscaran mining district, comprising the mountains Yuscaran and vicinity, is situated 72 km. south-east from Tegucigalpa and 144 km. from San Lorenzo on the Pacific coast. The lodes, which traverse igneous rocks, carry sulphides of

of silver, copper, zinc, lead, iron, etc., together with antimonial sulphide of silver, in a quartzitic gangue. Sulphides of silver

carrying some gold occur in the department of Choluteca, of Aramicina, near a town of the same name, 48

district

km. from the Pacific coast and about 137 km. from Tegucigalpa. The Guasucaran mine, a celebrated silver mine and one of the oldest in Honduras, lies 96 km. from the Pacific and Argentite and blende 48 km. south-west of Tegucigalpa. occur in a gangue of quartz and barytes. The country rock The San Baris stated to be a highly siliceous trachyte. tolo mines lie 90 km. north of San Lorenzo and 80 km. south-

The ore is free-milling quartz carrying of silver. The mines of San Andres and chloride sulphide are situated upon San Andres Mountain, north-west of The ore is said Tegucigalpa in the department of Copan. of silver Another group mines lies about to be free-milling. 15 km. from Tegucigalpa, and in 1891 was worked by the

west of Tegucigalpa.

Suyape

Silver

Concession,

Ltd.

The

ore

is

argentiferous

galena with blende and quartz. Ore carrying silver and gold occurs near the village of San Juan, in the district of Corpus, department of Choluteca. In the district of Santa Lucia, department of Tegucigalpa, lodes are worked by the Victoria, Zopilotiera and Santa Elena mines. Victoria

The

Zopilotiera lode carries argentite, and in the lode the silver-bearing minerals are arsenical and

iron pyrites.

Antimonial

silver ore, associated

with more or less gold,

occurs in the department of Tegucigalpa, 120 km. from the a city, and at about 144 km. from the same city, near

small village called Langue, ores carrying silver and lead occur. At San Marcos, 80 km. from San Lorenzo and near the town of Sabana- Grande, a free-milling ore carrying argentite and gold

is

east of brittle

The Santa Lucia mines lie 14 km. The lodes carry pyrite, argentite, and ruby silver, and a trace of gold. The ores said to occur.

Tegucigalpa.

MEXICO require a preliminary roasting

91

and are not adapted

to free

milling.

The silver from the whole of the Central America States in 1918 amounted to only 2,900,000 oz., an average of 483,000 oz.

per

The

annum

for each of the six countries forming those States.

total yield for 1919 is estimated at 3,000,000 oz.

MEXICO The

States

silver- producing

betically, are as follow

of

Mexico,

arranged alpha-

:

Aguascalientes [77]

At Asientos de Ibarra the country

is

hornblende-andesite

Other formations are limestone, schist and rhyolite. The principal veins strike N.6o-7oW. and dip N.E. or S.W.8o. According to Miguel Velazquez de Le6n, the silver ores are argentite, pyrargyrite and polybasite, with argenor diorite.

tiferous galena, blende, pyrite, chalcopyrite and bornite. The gangue is quartz. Other veins in the district run N.-S. or

E.-W. Tepezala, with similar formation, is a copper district, but the copper oxides and sulphides of some of the veins are silverbearing.

Chiapas

The Santa Fe mine McCarthy

[78],

is interesting,

the ore occurs in

channels in a large mass

as,

according to E. T.

in irregular courses or of wollastonite (lime silicate) surit

rounded by limestone. The principal useful minerals are argentiferous bornite and chalcopyrite, carrying more or less free

gold,

associated

with

tetrahedrite,

enargite,

pyrite,

galena, blende, with copper carbonate minerals as incrusta" " " blow " or tions in the vicinity of vent holes. The ore carries

from 6 to 8

oz. of silver

per ton.

The

ore-bodies are

usually regarded as contact deposits.

Chihuahua

The Santa Eulalia camp km.

south-east

of

of the Iturbide district lies

Chihuahua

city.

It

was

28

discovered

SOURCES OF SUPPLY OF SILVER ORES

92

in 1703.

The formation

stones largely covered

consists of folded Cretaceous lime-

by an unconformable mantle

of dacitic

The

ore-bodies, which are irregular in shape, are metasomatic replacements of limestone, mainly along bedding-planes, tuff.

The richest ores, consisting along fractures. of and oxidized ores of iron, occur cerussite, galena chiefly at depths of from 400 to 457 metres.

but

partly

In the Parral

of

camp

the

Hidalgo de Parral

district,

strong and well-defined veins in porphyry have been worked to a depth of 366 metres.

According to Waitz, the area between Parral and Minas Nuevas consists essentially of a foundation of schists, upon which rests, and through which penetrates, a series of Tertiary The schistose volcanic flows and minor intrusive rocks. formation, of schists,

which

rocks are tuffs

and

unknown

age, consists principally of siliceous The Tertiary igneous are considerably folded.

made up

of felspar-porphyry, andesites, rhyolites and The basalt, arranged in their order of appearance.

felspar porphyry occurs as intrusive rocks cutting through the schists and sending out apophyses in all directions. The

They are, for the most part, of the andesitic rocks was The extrusion considerably altered. followed by the appearance of rhyolites and tuffs, and afterwards by the formation of dykes and surface flows of basalt. Santa Barbara, 6 km. south-west of Parral, was discovered in 1547. The ore-deposits occur as lodes cutting through andesites occur as surface flows.

indurated grey shales and porphyries, which break through and overlie them. Generally speaking, the ores consist of galena, with pyrite and blende, in a gangue of quartz. the district in 1900, the Moctezuma Mining and Milling Co. was exploiting two lodes, carrying ore of the following average composition lead, 7-5 zinc, 6-5

When Weed examined

:

copper, 0-27

;

iron, 5-0

;

lime, 8-0

;

and

;

silica,

50-0%;

;

silver,

and gold, $1-40 per ton. Minas Nuevas is 12 km. north-west of Parral. The most important lode is the Veta Grande, on the Veta Colorada, which was located in 1645. At 305 metres in depth it is from 4*5 to 5-5 metres thick, and carries about 46 oz. of silver per

6 oz.

ton.

;

MEXICO

93

According to Robles, the more important system of lodes N.28W. and traverses rhyolitic rocks. A second has a direction N.43E. and traverses andesites. The system first system includes the Veta del Refugio, Santa Ana, Veta Colorada, and Veta Negra lodes. The principal minerals occurring in the Veta Colorada are argentite, pyrargyrite, native silver, anglesite, cerussite and galena in a gangue of quartz, with which is associated a small amount of fluorspar.

trends

The

lodes cut through all rocks with the exception of the and Robles considers that mineralization probably

basalt,

took place in Pliocene times. In the Andres del Rio district,

the Urique

mines were

discovered in 1630. N.-S. veins dipping E. traverse Middle Cretaceous limestones and slates. Polybasite, pyrargyrite, argentite, pyrite, galena and blende occur in a gangue of

Veins with a similar strike and quartz, calcite and gypsum. dip traverse Tertiary diorite. The gangue is quartz, and the ores are polybasite, miargyrite, pyrargyrite, pyrite and galena. Iron oxides and blue and green copper carbonates are found in

The mines of Batopilas were discovered N.-S. lodes course through diorite arid contain an abundance of native silver, argentite, pyrargyrite, miargyrite, proustite, pyrite and galena in a gangue of quartz and calcite. the oxidized zone.

in 1632.

In the Arteaga district (W.N.W. of Batopilas), a vein, at the Rio Plata mine, according to H. J. Baron [77/p. 547],

The

from 1-2 to 1-8 metres and native silver in a thick, argentite, bromyrite in shoots from which occurs The of bluish ore, quartz. gangue on the cm. thick to hanging-wall side, carries from 2*5 30-5 At the Palmarejo oz. of silver 200 to 4,000 per ton. mines the ores are argentite, with some stephanite in a siliceous gangue, carrying disseminated pyrite. The principal bonanza, according to T. H. Oxnam [77/p. 547], occurred at the interAt section of an E.-W. vein with one coursing N.5i3oW. and in diorite veins occur the hornblende-andesite, Chinipas The strike is N.E., or in some cases N.W. The vein-filling is quartz with argentite, pyrite, oxides of iron and dendritic

strikes

N.25W.

in diorite.

vein,

carries

manganese.

Ocampo,

in the

Rayon

district,

was discovered

in

1821.

SOURCES OF SUPPLY OF SILVER ORES

94

The country is porphyry, and the ores are siliceous, carrying At Pinos Altos (north of Ocampo) the silver and some gold. principal vein is 6 metres thick, and the silver values are greater than the gold values. In the Sahuayacan district (48 km. west of Ocampo) there is a narrow band of shale impregnated with argentiferous The veins pyrite, with an intrusion of andesite near by.

numerous and well-defined. Guadalupe y Calvo, of the Mina district, is a gold mine, but the ores contain about 16 oz. of silver per ton. The veins at Cerro Colorado form a network of altered hornblende-andesite. The gangue is calcite and quartz, carrying free gold, pyrite and chalcopyrite rich in silver. At San Jose de Gracia the lodes, which have a N.-S. course, and traverse hornblende-andesite, carry auriferous pyrite, galena, blende and silver sulphides in a are

gangue of quartz. Coahuila

The Sierra Mojada mines, discovered in 1878, are in the southern part of the State. The occurrence is very similar The formation is to that of Santa Eulalia (Chihuahua). Cretaceous limestone.

A volcanic breccia,

consisting of angular

and granite rocks, cemented by a siliceous matrix, rests unconformably upon the limestone. The ores lead carbonates, copper ores and silver chloride occur as replacement and impregnation deposits within the limestone, at and near its contact with the volcanic breccia. However, the most valuable ore-body ever mined in the camp the San Jose copper-stope was apparently an impregnation of the siliceous breccia with silver chloride and copper oxide, and occurred chiefly at the contact. The ore, considered as a whole, carries varying amounts of lead, silver, silica, iron, and sometimes copper, zinc, barium sulphate, sulphur and

fragments of

felsite

gypsum.

Durango In Guanacevi, according to A. F. J. Bordeaux [77/p. 556], a stockwork in hornblende-andesite impregnated is

there

with pyrite, and elsewhere, an altered rhyolite with intrusions

MEXICO

95

of andesite

dykes containing fragments of rhyolite, -forming a breccia, and reticulated with veinlets of argentite, etc. The minerals are pyrite, argentite, ruby silver, native silver, chalcopyrite with

The gangue

some arsenopyrite, galena, and blende in depth. is quartz and calcite. A little north of the town

of Guarisamey, the formation, according to E. Halse [79/p. 248],

eruptive quartz-hornblende-andesite, andesite breccia, and porphyrite with interbedded sheets and intrusive dykes of

is

The main lode

N.W. and The ore is argentite, argentiferous pyrite, chalcoSome of the ore consists pyrite, galena and ruby silver (rare). of wavy black layers alternating with lighter ones and having felsite of

the rhyolite group.

strikes

dips N.E.

a conchoidal texture.

much

This ore has frequently

resem-

country, and may the replacement of the latter by

blance to the fluidal structure of the

felsite

be regarded as evidence of quartz and argentite [80]. In the Candelaria mine, at San Dimas, the main vein strikes N.55E., dips N.W.5O and is from 1-8 to 2-4 metres thick ,

The

in brecciated felsite.

ores are argentite, proustite, native

and argentiferous pyrite in quartz and calcite. At Promontorio, which was discovered in 1880, the formation,

silver

according to F. C. Lincoln [77/p. 557], consists of rhyoliteporphyry with inclusions of andesite and dacite and segregations

(?)

of binary granite.

The vein

strikes

N.55W. and

dips

S.W., cutting the joint-planes of the country at an acute angle on both strike and dip. The primary minerals are quartz,

galena and blende, less pyrite, a

little chalcopyrite, and minute The secondary quantities of bornite, chalcocite and covellite. enrichment consists of native silver, chalcocite and a little Small amounts of copper minerals indicate a chalcopyrite.

The ore is arranged in shoots, which pitch south-east or follow the dip of the cross-fractures (N.E.-S.W., dipping steeply to the S.E.). high silver content.

At Mapimi, which was discovered in 1598, the formation, according to J. D. Villarello [77/p. 558], consists of Middle Cretaceous sedimentary rocks and a Tertiary eruptive rock (hornblende-andesite)

.

The primary minerals

are arsenopyrite,

galena, blende and pyrite, with calcite as gangue boulangerite, chalcopyrite, fluorspar and barytes are less abundant, while ;

SOURCES OF SUPPLY OF SILVER ORES

96

The stibnite, pyrargyrite, tetrahedrite and quartz are rare. above occur in chimneys. The Ojuela chimney is 40 metres in diameter, between 800 and 500 metres in depth, and descends almost perpendicularly to 650 metres. La Paloma chimney at a depth of 470 metres 600 metres.

is

horizontal, then descends vertically

At Copalquin the ore-deposits are contained in quartzAt Topia the veins extend N.E. and contain galena, a small amount of pyrite, argentite and pyrargyrite, blende, in a gangue of quartz and calcite. diorite.

Guanajuato

The mining district of Guanajuato is one of the oldest and most extensive in Mexico, and has yielded immense quantities of silver, as is shown by the following figures :

Value

of Silver Production,

1701-1800 1800-1900 1900-1903

.... .... ....

1701 $

to

1903

(Pesos)

279,690,689 231,137,013 6,235,204 ($10 = 1 approximately.)

The most productive years were 1791, 1804, 1849, I ^5o and 1852. The researches of Villarello, Flores and Robles on the geology of the Sierra de Guanajuato have given the folio wing results The oldest rock-group is formed of highly contorted argillaceous, calcareous and carbonaceous schists and conglomerates, :

identical in petrological characters with those of Zacatecas.

Into this metamorphosed sedimentary series were intruded, with attendant metamorphism, gabbros and olivine- and quartzdiabases. After a period of erosion there then followed a series of Tertiary extrusions in the following order (i)

Andesite rocks with

and

tuffs.

(2)

:

Rhyolites with rhyolitic

Hypersthene and augite-andesites " Red Conby the deposition of the after which there glomerate," appeared rhyolitic tuff, dykes of comptonite, and an outpouring of the Cerro Cubilete tuffs

breccias.

these were succeeded

(3)

;

MEXICO

97

Mineralization is believed to have been coincident with the extrusion of the Cerro Cubilete basalts. The lodes have been grouped into three zones, viz. the Central Zone, the Eastern Zone and the Western Zone. The basalt.

Central Zone, which includes the Veta Madre, which was discovered in 1558, is divisible into three systems. The famous

Veta Madre lode occupies a brecciated zone lying chiefly " " between the Red Conglomerate and the schists. In depth it traverses the schists where they are intruded by diabases. The Veta Madre is really a composite lode of considerable complexity, and frequent variations in dip and strike have been brought about by the variations in the nature of the rock Similar variations are to be observed in the Sta. traversed. " Red Conglomerate." Lucia and Sta. Ines veins within the At Esperanza, Protectora and La Cebada, the ore-bodies traverse schists and diabases. As example of the second of is the Cedro lode which the Zone Central there system traverses rhyolitic breccia and the hypersthene- and augiteandesites, and the veins of the Flores de Maria group, the S. Vicente, Sta. Anita, Canales and El Conejo lodes, which " Red Conoccur in rhyolites and rhyolitic breccias and the glomerate," are examples of those belonging to the third system. The Eastern Zone comprises the districts of Sta.

Rosa, San Nicolas del Monte, Peregrina, Villalpando, Cubo and El Nayal, and the Western Zone extends from San Cayetano

La Luz. The predominant minerals occurring

to the district of

Sierra de

in the lodes of the

Guanajuato are polybasite, stephanite, and pyrite in a gangue of quartz with some calcite. of oxidation is very superficial.

argentite

The zone

Guerrero

Tasco

is

one of the oldest and one of the most important

mining camps of the

district of Hidalgo.

calcareous schist and limestone cut by At Tehuilotepec (which forms part of the Tertiary eruptives. Tasco camp) the formation is mainly limestone cut by andesite and rhyolite.

The formation

is

SOURCES OF SUPPLY OF SILVER ORES

98

According to J. O. Aguilera [77/p. 567], the veins of Tasco are related to these eruptives. According to E. Halse [81], the veins run (i) N.N.W.-S.S.E., dip E.S.E. (prevalent) (2) N.W.-S.E., dip N.E. (prevalent) The veins usually meet at acute angles on (3) N.-S., dip E. ;

;

the line of strike, and rich branches or shoots of ore occur at the points of intersection. The filling consists of marcasite, pyrite, blende, galena, chalcopyrite, argentite in a gangue of quartz and calcite.

and proustite

In Tetipec (including Poder de Dios, Pregones and Xocotitlan) " country," filling and structure of the veins are similar. The principal direction of the veins is N.W.-S.E., as in the

Tasco.

The

lodes of the Rosario mines

mine are

in hornblende-andesite.

and the San Nicolas del Oro They course N.W. and some-

times N.E., and contain, below the zone of oxidation, argentite, ruby silver, pyrite and a small quantity of chalcopyrite.

The gangue is quartz carrying gold. At Tlalchapa the lodes have a N.W. course and dip to The vein- filling is quartz with argentite, p^rite the N.E. and blende. Occasionally calcite, galena and chalcopyrite occur.

The veins worked by the Coronilla mines are in rhyolite, and contain argentite, ruby silver and pyrite in a gangue of quartz.

At the Tepantitlan mines the veins traverse red conglomerate of Tertiary age. They have a N.W. course and dip to the N.E. or to the S.W. The gangue is quartz, containing argentite, ruby silver, blende, arsenopyrite and a small amount of chalcopyrite.

In the Campo Morado range of the Aldama district, large masses of pyrite occur in sedimentaries of Archaean (or possibly Palaeozoic) and Cretaceous ages, in relation to a dioritic dyke. According to Luis Hijar y Haro [82], the outer shell of one

enormous prism consists of oxidized ores, cerussite, anglesite, and silver contents about equal. The prism probably contains on an average 0*25 % silver and iron oxide, etc., with the gold

0-005

% gold.

The

deposit

is

a primary one.

MEXICO

99

Hidalgo

Pachuca and Real del Monte are nearly 5 km. apart and about 100 km. north of the City of Mexico. The Pachuca district lies on the western slope and Real del Monte on the eastern slope of the Pachuca range of mountains, which bounds the great Valley of Mexico. From 1522, when Pachuca was discovered, to 1901, more than 3,500 tons of silver, worth about 31,000,000 sterling, are said to have been extracted, principally from the immense bonanzas. The Pachuca Range is built up of Tertiary andesite, rhyolites and basalt, probably of Miocene age. The outpouring of andesite, which forms the principal rock- type, was followed by rhyolite, with associated obsidian, pitchstone and tuffs, and finally by basalt. The lodes, usually found in andesite, The are younger than the rhyolite, but older than the basalt. country near the lodes is kaolinized, impregnated with silica,

and otherwise considerably altered [83]. The veins, according to Aguilera and Ordonez, belong to one E.-W. system of fractures only, but secondary veins branch off from and sometimes diagonally unite the E.-W. veins at angles seldom exceeding 30.

The veins

are fissure veins with

a quartz gangue. There are five main groups of lodes, namely, the Vizcaina, El Cristo, San Juan Analco, Santa Gertrudis and Palo Norte. The width of the lodes seldom exceeds 7 metres, but they are

remarkably persistent along the strike. The upper oxidized (Colorado) zone consisted of quartz, oxides of iron and manganese, and chlorides and bromides of silver, which were capable of treatment by the cold amalgamation or patio process (invented in Pachuca in 1557 by Bartolome de Medina). Exploitation is now confined to the lower sulphide (negro] zone, which consists of pyrite, galena,

and rhodonite. Blende is Sometimes stephanite and polybasite occur. The gangue is milky quartz, with, in places, bluish, rare. Calcite occurs only in small greenish and purplish varieties. amounts as a later infiltration. Native silver is found at all depths. Dark ruby silver argentite

J

SOURCES OF SUPPLY OF SILVER ORES

ioo

(pyrargyrite) is rare, and light ruby silver (proustite) appears to be entirely absent from the Pachuca veins. In Pachuca, bonanzas have occurred more frequently in the lower than in the

upper zone.

The San Rafael bonanza produced nearly

$14,000,000 in ten years, whilst that of Rosario $28,000,000 in thirty years (1853 to 1883).

produced

At Real del Monte N.-S. veins intersect the E.-W. veins. At a depth of 400 metres the filling of the Vizcaina vein is quartz, coarse blende, fine-grained argentiferous galena, pyrite, chalcopyrite and rhodonite. The Santa Ines (N.-S.) vein

has been worked to a depth exceeding 400 metres, and has two shoots of rich ore in the sulphide zone which appear to pitch south [84]. Jalisco

At Hostotipaquillo, the lodes are formed by the

siliceous

replacement of brecciated andesite.

According to S. J. Lewis [20/p. 523], the primary filling consisted of metallic base sulphides with some silver, the gangue being calcite, a little quartz and then followed siliceous solutions containing rhodochrosite more of the precious metals this was followed by oxidation ;

;

and enrichment.

Here and

there, through step-faulting, quartz has been shattered, displaced from 3 to 6 metres, leached. Rich ore occurs to a depth of 200 metres from to 300 metres the ore shows little secondary influence, but still be worked at a profit. ;

The Amparo mine, near

is

Etzatlan,

in

the

and 200 can

augite-andesite

(basic rock).

In the opinion of S. J. Lewis [20/p. 526], the San Juan lode, striking N.S. and dipping W.7O, was first formed, the primary

and copper sulphides, and abundant rhodochrosite in a gangue of calcite. This vein was subsequently cut through and displaced 90 metres by the Dulces Nombres vein, trending N.W.-S.E. and .70. Owing to the draining of the ground and the dipping low-grade

filling

consisting of lead,

zinc,

iron,

re-opening of the channels, this section of 300 ft. in length became much enriched by a siliceous solution containing gold Finally there was a great fault movement in the the rock breccia was southern portion of the San Juan vein

and

silver.

;

MEXICO

..

,

,,,,,,

101

ground up into impalpable powder by the up arid clown movement, and a gouge (flucari) from 30 cm. to I m. in thickness was formed in the fault zone, which acted as a check across the ore- channels, thereby causing heavy ore deposition on both sides of the fault. There are two ore-bodies, one of which goes The ore contains an average of to a depth of 300 metres. 5 dwt. gold and 9*6 oz. silver per ton.

Territory of

Lower California

In the Cacachilas district the veins are in a granitic rock.

The gangue is quartz. In the upper zone are oxides of antimony and iron, chloride and bromide of silver, and carbonate of lead

in the sulphide zone are galena, tetrahedrite, sulphides of silver, berthierite, jamesonite, pyrite and blende. In the San Antonio district, according to Santiago Ramirez, ;

N.E.-S.W. veins, dipping

The sulphide

ores are

S.E., occur in granulites and diorites. similar to those of the Cacachilas

district [86/p. 343].

In the Virgenes district (32 km. east of La Paz) the formation is tourmaliniferous granite traversed by dykes of

pegmatite

(?).

According to Santiago Ramirez the veins

N.20W. and

course

dip

E.

The

ores

are

silver-bearing

and galena, accompanied by copper minerals. The gangue is quartz or heavy spar [86/p. 346]. At the Pihuamo mines the lodes course E.ioN. and dip N.ioW.65. The gangue is calcite, and the ore is silverbearing galena and blende. The ore-bodies lie at the contact between slates and limestone of the Lower Cretaceous above, and granulites below. tetrahedrite

Mexico

At El Oro, the formation (Cretaceous), from 500 to 900 intrusive andesite of about 1,000 of 2,200

ft.

ore-bearing.

63-70. follows

:

consists ft.

ft.

of

calcareous

shale

in

thickness, overlying in thickness. At a depth

shale again appears, and may possibly prove to be The veins strike N.io-2OW. and dip W.

S. J. Lewis [25] gives the history of the lodes as After the fracturing of the shale by the andesite,

SOURCES OF SUPPLY OF SILVER ORES

102

the primary mineralization was performed by alkaline solutions no doubt aided by the carbonaceous matter in the shale

and

calcite

was the gangue carrying

little

of

the precious

then followed cross-faulting and the entry of a siliceous solution far richer in the precious metals (pseudomorphs of quartz after calcite occur) finally, owing to the wearing away of the surface cap of andesite, circulation of the surface waters in the cross-channels has produced enrichment of the ore-bodies, forming them into the bonanzas that are being mined to-day. metals

;

;

The

which occurs in a fine state of division, is alloyed and is mixed with minute proportions of argentite, proustite and pyrargyrite. At Sultepec, the Cretaceous shale, from 300 to 600 metres thick, is underlaid by intrusive andesite, in which the lodes become impoverished. with

free gold, silver,

According to E. Halse [87], the country is a green talcose often accompanied by andesite dykes. The ores are

schist,

pyrite, marcasite, argentite, pyrargyrite, proustite (occasional),

miargyrite

galena and blende, accom-

stephanite

(rare),

panied by

chalcopyrite, stibnite (rare)

gangue

is

quartz, calcite,

At Zacualpan, the

(rare),

and arsenopyrite. The dolomite, fluorspar and barytes (rare).

principal lodes strike N.-S. in andesite

with inclusions of Cretaceous shale, which has an adverse effect on the lodes. The pay-ore, in the opinion of S. J. Lewis [26], is largely a matter of secondary enrichment, which will probably prove to reach to 450 metres in depth. Two systems of veins occur in Temascaltepec E.-W. (the

and N.W.-S.E.

(low grade). According to Dollfus and Montserrat [88], the country is a blackish schist with The veins, calcite, and is near a mass of quartzose porphyry. as regards filling, are very similar to those of Sultepec. best)

In the Ilaltaya group, according to Hoppenstedt, the ores

form contact- deposits between andesites and Tertiary volcanic conglomerates.

Michoacdn

The

principal veins at Tlalpujahua, according to Joseph The country [85/p. 75], strike N.25W. and dip E.

Burkart is

a metamorphosed schist or

slate.

The

filling

consists of

MEXICO

103

native gold and silver, argentite, polybasite and pyrargyrite, with pyrite and occasionally calcite. The usual gangue is

Dos Estrellas, one of the richest mines of the Republic, geologically forms part of the El Oro district (see State of Mexico). The ore milled contains 7 or 8 dwt. of gold and from 4 to 6 oz. of silver per ton. At Angangueo the veins The silver occurs mainly as are fissures in eruptive rock. The gangue argentite, with galena, blende and chalcopyrite. is quartz and calcite. quartz.

Nuevo Leon

The ores in this State are principally silver- bearing galena and blende. According to J. O. Aguilera [77/p. 596], the Iguana ore-deposits are bedded veins carrying quartz, galena, pyrite and silver sulphides in limestone near diorite. Oaxaca According to E. Halse [8g/p. 372] the country at Taviches hornblende-andesite (Tertiary), traversed by dykes of diorite, trending, like the veins, in a general N.W.-S.E. direction, and which are metalliferous in places. Pyrargyrite is the It is frequently associated with auriferous principal silver ore. is

and is occasionally accompanied by polybasite, argentite and stephanite. Stibnite, galena, chalcopyrite and blende are also found. The gangue is quartz, with calcite and gypsum Dark ruby silver (pyrargyrite) occurs in spots occasionally. bunches (ojos), and sometimes forms the and little (moscas)

pyrite,

centre of quartz, having a radiated spherical texture (rueda), which appears to have filled cavities in the rock [80] .

Gold-bearing ores,

carrying some silver, occur at Peras and rocks, and argentiferous lead- ore deposits

at Pefioles in granitic are found at Tehuantepec.

Puebla In the Teziutlan and Tlatlaquitepec districts, contact copperOn bearing deposits occur between gneiss and mica schist. an average the ores carry 3 oz. of silver and i dwt. of gold per ton. 8

SOURCES OF SUPPLY OF SILVER ORES

104

t

Queretaro

At Cadereita, the old mine of San Juan Nepomeceno (or Mina Grande del Doctor) produced a large quantity of silver the

during

Colonial

period.

In

the

seventeenth

century

have paid more than 18,000,000 pesos as the King's fifth. According to C. B. Dahlgren [90], the vein strikes E.-W. and dips S.6o in limestone. The ore now being worked in the upper levels is siliceous, and contains both silver and said to

it is

gold.

The Ajuchitlan mine,

in the Mineral de las Aguas, is, according to S. J. Lewis [55/p. 448], a true contact deposit, consisting of tongues of intrusive porphyrite in Cretaceous calcareous

The latter was shattered by the eruptive mass, primary mineralization of gold-silver ores from a siliceous solution followed, and quartz-breccia ore-bodies were formed by replaceshale.

This stage was accompanied by settling and was by cross-faulting, while enrichment has succeeded the

ment.

followed latter.

San Luis Potosi

The Barreno mine

in the

San Pedro

district is

a true contact

deposit of Cretaceous limestone overlying intrusive dioriteporphyrite (probably Miocene). The lead-silver-gold ores

were deposited in immense fractures in the limestone. S. J. Lewis [55/p. 444] regards the lodes as having been built up as follows (i) A deposition of primary iron sulphides from a siliceous solution with low precious-metal contents (2) a considerable shattering of the limestone, which preceded and :

;

accompanied the entry of

siliceous solutions

carrying lead, and other base zinc metals, with mercury, antimony, arsenic, an increase in gold and silver (pseudomorphs of galena after

and pyrite occur) ore-bodies sulphide ;

(3)

the oxidizing enrichment of the iron-

by atmospheric and

circulating agencies,

which has reached a depth of 300 metres. Catorce was discovered in 1772.

The

veins traverse lime-

stone and porphyry dykes, and are themselves cut by more recent porphyry dykes. The general strike is N.W.-S.E., the

dip S.E. or

N.W.6o

to

65.

The

negros zone contains proustite

MEXICO and other

rich silver ores,

105

with sulphide of antimony and

The chalcopyrite, pyrite, galena and some blende. gangue is more quartzose than in the colorados or oxidized zone. arsenic,

At Santa Maria is

country strike N.4O

The ore

del Rio, according to J. P. Manzano, the Cretaceous slate [77/p. 611]. The veins vary in to

75W. and

in

dip from

N.68

to

8.67.

argentite and pyrargyrite, and accompanied by pyrite chalcopyrite in a gangue of quartz and steatite. At Charcas the formation is limestone, and the ores contain copper, zinc and antimony, with some silver. At Ramos, La Cocinera vein, discovered in 1796, produced silver to the value of 21,000,000 pesos from 1801 to 1809. The country is an argillaceous schist. The ores are native silver, polybasite, cerargyrite, argentite and proustite, accompanied by tetrahedrite, chalcopyrite, pyrite, galena and blende in a gangue of quartz and clay. consists of tetrahedrite,

Sinaloa

At

Fuerte,

silver-bearing

veins

occur

in

porphyry and

Palmerito, about 48 km. north of Culiacan, is in the district of Mocorito. Here, according to W. H. Weed [77/p. 614], there is a breccia reef of decomposed trachyte, syenite.

striking E.-W. and dipping thick. The hanging-wall is

N.30, and from 41 to 46 metres quartz-syenite, and the footwall is altered trachyte. Argentite and galena are the principal ores. The whole ledge is said to average 15 oz. of silver per ton. The output amounted to between 4,700 and 6,000 oz. per month in At Cosala the country is andesite, carrying much lime. 1900. All the ores carry silver, gold and some copper. The gangue is quartz. About 25% of the value of the content is in silver. At Santa Cruz de Alaya, 48 km. north of Mazatlan, the formaaccording to E. Halse [79/p. 243], is limestone, probably of Middle Cretaceous age, containing thin bands of chert and intercalations of schist. The principal veins course N.-S. and tion,

dip

W.

The

ore consists of argentiferous blende, with some and arsenopyrite, and occasional spots of

pyrite, chalcopyrite

argentite

and ruby

silver in

a gangue of quartz and

calcite.

106

SOURCES OF SUPPLY OF SILVER ORES

The veins

are of the replacement type and often consist of bands separated by limestone. The ores carry from 19 to oz. of silver per ton. 40 The vein of the Jocuistita mine, district of San Ignacio, of ore

strikes E.-W. and dips N.83. The formation is porphyry and trachyte. At Copala, district of Concordia, the formation consists of Tertiary eruptive rocks. The veins strike N.-S. and dip E. The filling is quartz, which carries small quantities of argentite and native silver, with a little pyrite, galena and gold. The Tajo mine, district of Rosario, was worked by the Spaniards. The vein strikes E.-W., and the ore consists of argentite, native gold and silver, galena, pyrite and blende

in quartz [QO/p. 92].

Sonora

The Babicanora camp, district of Arizpe, was discovered The country is porphyry. The principal lode 1780. strikes N.52W., and dips W.75. The ores are sulphide of silver with gold and pyrite. According to the late Edmond Fuchs [91], one vein of the Carmen mine carries proustite, argentite and polybasite, with a little gold, associated with

in

pyrite, a little

galena,

chalcopyrite and

tetrahedrite

quartz and a little calcite. Some silver in the ores of the Cananea copper deposits.

The gangue

is

The Chipionena mine district of Ures.

N.W.-S.E.

and

is

(rare).

found

26 km. north of Matape, in the According to E. Halse [89], the vein strikes The ores are in granite. dips N.E.45 lies

The ore occurs silver-bearing galena, pyrite and blende. crossin shoots pitching N.W. or following the joints in the country.

The

silver-bearing veins,

worked by the San

Javier,

Los

Bronces and La Barranca companies, traverse sandstone and

and contain chalcocite, tetrahedrite, pyrite, chalcopyrite, blende and a small amount of galena, and complex sulphides of silver in a gangue of quartz and calcite.

slate,

MEXICO

107

Tamaulipas In the Victoria district the ores carry silver-lead-copper. is a copper district, but the ores contain some silver.

San Jose

Territory of Tepic

Rich gold-silver veins occur in the municipalities of Santa Maria del Oro, Acaponeta and Santiago Ixcuintla, with or without copper and lead. El Zopilote mine, in the last municipality, has veins with a N.W. course consisting of quartz, blende and pyrite, sulphides of silver and small amounts of galena. The Castellana mines, to the north of Ixtlan del Rio, have lodes with a N.5oW.

They contain quartz, pyrargyrite, polybasite and a amount of argentite. Native silver occurs in the qxide At Barranca del Oro, in Ahuacatlan, the veins are in zone. granulites cut by dykes of diorite and hornblende-andesite. The lodes have an E.-W. course, and contain quartz, pyrite and a little galena. course.

small

Zacatecas

was discovered by Juan de Tolosa The Zacatecas in 1546. The extension is 14 km. from north to south, and 12 km. from east to west. district

Values of Production in the Zacatecas District 1548-1810 1810-1818

1818-1825 1825-1832

..... ..... .....

Among the mines famous may be mentioned La

for their

$ (Pesos)

588,041,956 20,060,363 17,912,476 30,028,540

remarkable output of

Gallega, San Acacio, San Borjas, Asturiana and San Francisco, all in the Veta Grande lode, Quebradilla, Rondaneva and Guadalupe, on the Mala Noche lode, and the mines exploiting the San Luis and Santo Tomas silver

veins.

According to Burckhardt and Scalia, the oldest rocks in the Zacatecas region are ancient, highly-contorted sericitic

SOURCES OF SUPPLY OF SILVER ORES

io8 schists.

Of

later origin, and unconformable to the above, are grits and siliceous and argillaceous schists of

quartzites, Triassic age, exposed only at or highly-inclined.

Upper

two

points,

and folded

Exposed over a considerable area to the west of the town an upper and lower series of spilites (altered

of Zacatecas is

shaly-olivine-basalts) intercalated with the Triassic sediments

and folded with them.

The upper

series rests unconformably and the lower series of spilites. upon both the ancient schists The outpouring of the upper spilites was followed by a lengthy period of erosion during which the roca verde grits and breccias were laid down. Afterwards came the Bufa rhyolites and rhyolitic tuffs and breccias as extensive surface flows, but now represented by a few uneroded remnants, and, finally, quartz-porphyry and rhyolite, as unimportant dykes traversing schists and spilites, now represented by occasional outliers

at elevated points. Flores distinguishes

three principal mineralized zones the middle zone, which includes the mines working the Vet a Grande lode the north zone, including the mines of Panuco and the south zone close to the town of Zacatecas. The south ;

;

be grouped into several systems. The first includes Mala Noche, El Bote, Magistral, Sierpe and Plata, Cantera, all of whose lodes strike E.-W. The Cantera group is located for the most part between the roca verde breccia and the spilites the Mala Noche lode lies mostly within the spilites, and the El Bote and Magistral zone

may

;

groups traverse the ancient schists. The N.W.-S.E. system of lodes include the Quebradilla, San Luis, Santo Tomas, San Vicente and Dolores groups. The predominant primary minerals of these lodes ar-e argentite, proustite, polybasite, galena, blende, pyrite, chalcopyrite and bornite in a gangue of quartz with calcite. The secondary

minerals include oxides of iron, argentite, native silver and copper, and the oxides of copper. Cerargyrite, bromyrite, cerussite and the oxide of manganese are rarer.

According to E. Halse [92], there is a gold-silver-bearing group of veins to the south of the town. The strike varies from N.i4W. to N.28W., and the dip is easterly from 55

MEXICO

109

The country is a highly altered schist, often chloritic, The veins, about i metre thick on an (?). a banded have structure, the filling being characteraverage, ized by alternate layers ^f quartz and calcite, with ribbony bands of silver sulphide and native gold deposited preferably in the quartz. The veins carry from 6 to 38 oz. of silver and to

80.

with diorite

from 9 to 60 dwt. of gold per ton. The mines at Fresnillo are about 64 km. south-west of Zacatecas City. According to B. Silliman [77/p. 644], the deposit is a stockwork of some sixty veins resting in the N.E. and S.W. slopes of the Cerro de Proafio Mountain. The formation consists of Cretaceous limestone with dykes and intercalations of rhyolite. The veins average 60 cm. in thickness, and the walls for 90 or 120 cm. are impregnated with pyrite, The cerargyrite, native silver and argentite (azulaques). gangue

is

pyrite, etc.

white quartz. The sulphide ores are argentite, The lodes cut diorites, and, according to Arenas,

rhyolite also.

Sombrerete was discovered by Juan de Tolosa in 1555.

The

veins strike

slate

E.-W. and dip S.8o

and porphyry. is

Proustite

is

in

compact limestone,

the

abundant, and the gangue

characteristic

ore,

is

quartzose. Aranzazu, formerly known as Mazapil, was discovered in Here strata of Cretaceous- Jurassic age are, according 1530.

arsenopyrite

to

Ordonez

[84]

intruded by quartz monzonite of Tertiary is confined to the contact zones in

Mineralization

age.

limestone against the igneous rock. of

lite

ore-bodies consist

small amounts pyrite, tetrahedrite, galena, in a gangue of calcite, garnet with tremo-

with

chalcopyrite,

and and quartz.

of blende

The

The ore-bodies

therefore possess the charac-

contact-metasomatic deposits. The chief mine is Albarradon the vein strikes N.E.-S.W. and dips 8.85 in felspathic porphyry, near limestone and slate.

teristics of

;

ores, principally cerussite and galena, contain 40 oz. of silver per ton, but rich copper ores, as well as some gold occur also. The geological formation of the ore-bodies of

The

Santa Rosa and Concepcion del Oro is very similar. At Pen6n Blanco the veins cut Cretaceous limestone. They contain quartz, calcite and barytes and, in the zone of oxidation,

no

SOURCES OF SUPPLY OF SILVER ORES

native gold and silver, carbonates of copper and silver sulphide. In the sulphide zone are found argentite, stephanite, polybasite, stromeyerite, pyrargyrite, galena, pyrite, chalcopyrite and arsenopyrite. The lode at Mezquital del Oro, in the

Juchipita district, has a N.E. course and dips N.W. In the oxidized zone are quartz, iron oxide and free gold and, in the sulphide zone, quartz, chalcopyrite, pyrite and sulphides

The country is rhyolite. Mexico produced 63,656,000 oz. of

of silver.

silver in 1920.

UNITED STATES During the year 1919 the production of States

amounted to 56,682,445

$63,533,652 (valued at oz.,

$1-12 per indicates a

oz.,

oz.).

silver in the

United

having a value of Compared with the

reduction amounting to and represents the smallest output since

output in 1918 this 11,127,694

fine

Below are given the more important statistics relating to production, value, imports and exports of silver for the United States.

The following table gives the amounts of silver produced in the United States to 1920, inclusive,

and values per ounce from the years 1913 compared with some previous years :

the terms of the Pittman Act and U.S. Mint regulations domestic produced and reduced in the United States after Jan. 17, 1920 is saleable to the Director of the U.S. Mint at $i oo per fine oz. (Min. Jour., Jan. 29, 1921). 1

By

silver

The

following table gives the output

of

silver

by States

UNITED STATES for the years 1916 to 1920.

joint preliminary estimate

in

The by

figures for 1920 represent a the Bureau of the Mint and

the Geological Survey.

Silver Produced in the United States 1916-20, in

1

The

Fine Ounces

Including 4,144 oz. from Maine.

table on p. 112 gives figures relating to the imports

and exports

in the year 1919.

As regards the manner of occurrence and mineral contents of the very numerous silver-bearing deposits in the United States, space will only permit of a brief survey with the object of demonstrating their more important characteristics. With this in

held

view one cannot do better than summarize the opinion

by Waldemar Lindgren, a recognized authority on the

gold and silver deposits of America [93].

H2

SOURCES OF SUPPLY OF SILVER ORES Value of Silver Imported and Exported for Year Ended Dec. 31, 1919

(Figures furnished

by the Bureau

of Foreign

and Domestic Commerce.)

On the basis of geological occurrence, Lindgren distinguishes three types of silver-bearing deposits, viz. I. Veins contained in granitic rocks or accompanied by :

porphyries consolidated at considerable depth. The normal gangue is white massive quartz through which the sulphides are sparsely disseminated. II. Veins contained in volcanic surface flows, such as rhyoThe gangue is prevailingly very lite, andesite and basalt. fine-grained, chalcedonic, or drusy, adularia. The metallic

contains

and

in

many

constituents

accompanied by very small amounts of and copper sulphides.

argentite,

places it consist of lead, zinc

III. Metasomatic deposits in limestone, generally in connection with granite, diorite, monzonite or porphyry. Both quartz and calcite appear in the gangue. Almost without

exception the ores contain lead and usually also copper and Native silver and cerargyrite (horn silver) are abundant. zinc. Deposits of the first type are apt to be rich near the sur-

where secondary sulphides and sulphantimonites have formed, but generally they are disappointing below the water level, where the primary ore is reached. Many examples of face,

UNITED STATES be found

Montana, Idaho, and other States. is formed by veins which contain more abundant sulphides, among which galena generally predominates, and may be successfully worked by concentration even below the surface zone of enrichment. Examples occur in Clear Creek County, Colorado. Deposits of the second type, by oxidation and secondary deposition of sulphantimonites, have undergone great enrichment in their upper parts. Illustrations of this are found in the Tonopah and Comstock ores of Nevada, the Mogollon ores of New Mexico, and the Silver City ores of Idaho. this

A

type

may

in

subdivision of this class

The upper parts

deposits belonging to the third type are extremely rich, as exemplified at Leadville and Lake of

many

Valley. Geological Classification of Silver derived from Various Ores in the United States for 1906 [93]

The

United States considerations. on based metallurgical satisfactorily Lindgren recognizes two main groups, dry or siliceous ores

is

classification of the silver ores of the

most

and

silver base

metal ores.

silver- lead- copper ores,

The

siliceous

ores include

the

the silver-gold ores, and the true silver

H4

SOURCES OF SUPPLY OF SILVER ORES

and comprise those which contain little or no copper, In the main they are siliceous ores containing and silver. The value of the silver is equal to or only gold greater than that of the gold, and the copper and lead are below 2% % and 4^ The silver- gold ores conrespectively. tain gold ranging from 0-5 to 3 oz. per 100 oz. of silver. The ores,

lead or zinc.

%

true silver ores contain less than 0-5 oz. of gold per 100 oz. Among the silver base metal ores, those containing

of silver.

i%

or more of copper, equivalent to 50 Ib. per short ton, 2 are designated copper ores, whilst those with over 4^% of lead, or 90 Ib. per ton, are called lead ores.

The following tables give the relative proportions and actual production of the chief classes of ore produced during the years 1916 to 1918 in the United States :

Sources of Silver in United States (From

different classes of ores.)

The productions from the various year 1918 are in fine oz. as follow

Total

The

classes of ore for the

:

68,058,952

following are additional details concerning the sources classes of ore were derived during the

from which the various year 1918.

UNITED STATES

115

Dry or Siliceous Ores. About 42 % of the total production came from Nevada (chiefly from the Tonopah district), 22% was from Colorado (mainly from Leadville, Upper San Miguel, and Sneffels districts), and 18% from Utah. Montana and Arizona each produced more than 900,000 oz. of silver from this source, and New Mexico nearly 380,000 oz. Ninety-nine in was from Texas siliceous silver of the cent, produced per silver ores.

A large part of the silver from silver-gold siliceous ores is obtained with the gold by amalgamation and cyanidation in the mills, and the silver is recovered by refining the The remainder is produced by smelting the mill bullion. richer ores

and

refining

the

copper or lead bullion

pro-

duced.

Copper Ores. Silver is obtained from most of the copper ores, which are mainly sulphides, by the electrolytic refining of lake and blister copper produced by smelting.

Lead Ores. The principal yield of argentiferous lead ores comes from Idaho and Utah. The yield in Idaho is mainly from the silver- lead ores of the Cceur d'Alene, and in Utah from the Park City and Tin tic districts. Colorado ores of this type are derived from Aspen and Leadville. Most of the output is from the desilverization of lead bullion derived from the smelting of western ores and concentrate. The silver from argenZinc, Lead-Zinc and Mixed Ores. mainly as refinery by-products zinc concentrate from Colorado,

tiferous zinc ores is obtained

from

the

smelting

of

and Nevada. The silver from lead- zinc ores comes chiefly from concentrate from the Cceur d'Alene in Idaho, the Butte district in Montana, and the Park City region in Utah. Copper-lead and copper-lead-zinc ores were, during 1918, mainly derived from Utah, New Mexico, Colorado, California and Arizona.

California

Having obtained a general idea to

of the silver- bearing deposits

may now be turned a more detailed consideration of the several States from

in the

which

United States as a whole, attention silver is obtained.

SOURCES OF SUPPLY OF SILVER ORES

ir6

Montana This State

is

the leading silver producer in the United compared with the

States, but records a decrease in 1919 production in 1918. As in past years,

came from copper

much

of this silver

but a large part of the increase resulted from residues from zinc ores, both those smelted in the East and those treated in the electrolytic plant at Great Falls. The principal contributors of silver in 1919 were the combined Anaconda properties with the Butte and Superior, the North Butte, the Elm Orlfc, the Davies Daly and the East Butte. In 1918 the copper ores yielded oz. 10,521,219 (an average of 1-64 oz. per ton), of which Silver ores,

Bow County (Butte) supplied 10,480,556 oz. ores produced 4,532,034 oz., of which Silver

The

lead-zinc

Bow County

supplied 4,261,041 oz., and Lincoln County supplied 156,887 oz. or siliceous ores produced 1,028,443 oz., of which

The dry

Granite County supplied 465,631 oz. At the town of Butte, in south-western Montana, both

copper and silver lodes occur. The latter, which are no longer worked, contain silver sulphide ores, with some native silver, blende, pyrite, galena, quartz, rhodochrosite, rhodonite and hiibnerite. They have a marked banded structure. The copper lodes contain quartz as a gangue, whilst the metalof challiferous portions consist on an average of about 60

%

cocite,

30%

8%

enargite, tetrahedrite.

bornite,

and

2%

chalcopyrite, is

made up

of Tertiary igneous rocks intruded into Cretaceous

metamor-

covellite

and

phosed limestones,

etc.,

The most important "

The mineral region

and

lodes

is partly covered by rhyolite. are found in quartz-monzonite,

Into the quartz-monzonite were intruded, as later differentiated products, a granite- aplite, the " " Medoc Bluebird granite," and a quartz-porphyry, the the

Butte granite."

'

'

The rhyolite constitutes the latest phase of igneous The Mineralization pre-dated the volcanic phase. lodes, which are divisible into three groups, cut the aplite and quartz-porphyry dykes, but are older than the rhyolite. The porphyry. action.

formation of extensive oxidation and cementation zones are of great economical importance.

UNITED STATES Nearly

all

the silver-lead ores in

117

Montana occur

in fissure

veins in or about the contacts of intrusive quartz- monzonite stocks, and a few deposits are contained in limestone.

Utah

produced in Utah is a by-product obtained copper and lead ores. In 1918 the largest production came from Juab County, Salt credited with 4,994,806 oz., mainly from lead ores. Lake County had the next largest output, amounting to

Most of the

silver

in the smelting of

Of the oz., from copper, lead and zinc-lead ores. Lake County output of silver, the 'Bingham district produced 81%. The Tintic district, in Juab and Utah counties, yielded 6,681,644 oz mainly from lead ores. The Park City region, in Summit and Wasatch counties, produced Al2 572,586 oz., mainly derived from lead and lead- zinc ores. silver the of lead ores of Utah oz. together, yielded 6,672,725 3,022,638 Salt

->

>

in 1918,

the copper ores 1,445,559 oz -> tne lead- zinc ores The 1,243,638 oz., and the dry or siliceous ores 3,987,068 oz. crude ore smelted in 1918 contained 10,612,588 oz., and concentrate contained 2,316,766 oz.

At Bingham Canon contact-metasomatic copper deposits occur in limestone in the neighbourhood of late Mesozoic or Lodes accompanied early Tertiary monzonite. tion zones also occur in monzonite.

by impregna-

The silver base metal ores of Tintic and Park City are derived from replacement deposits in limestone associated with intrusive rocks.

Idaho

The output of Idaho showed a decrease of 38% in 1919 compared with the figure given for 1918. Decreases amounting to 300,000 oz. or more were shown by the Hercules, Morning, Smaller decreases were Hecla, Tamarack and Custer mines. the Bunker and Gold Hunter. Caledonia Hill, reported by The largest silver producer in the State was the Bunker Hill and Sullivan mine, followed by the Hecla mine at Burke. Other important silver producers were the Morning, Tamarack and Custer, Gold Hunter and Caledonia. The

n8

SOURCES OF SUPPLY OF SILVER ORES

mines in the Coeur d'Alene district produced about 4,800,000 In 1918 oz., or about 84% of the total output of the State. lead ores contained 88 of the total output of silver, and leadzinc ores 9%. Crude ore shipped, which averaged 15-61

%

oz.

of silver a ton, supplied nearly

32%

concentrate, which averaged 19*66 oz. of tained more than 67 of the total silver.

of the silver, and silver a ton, con-

%

The

silver- lead deposits

northern

Idaho

consist

of

the Cceur d'Alene district in

of

argentiferous galena, siderite, blende, pyrite, etc., in a gangue of quartz with some barytes. The district is composed of Algonkian slates and quartzites

pierced by a large syenitic intrusion. The lodes are later than the syenite, but, with the exception of the Hecla lode, older than a series of intrusive basaltic rocks which traverse

The

ores of

it.

Silver

City in Owyhee County occur in connection with surface flows of lavas. In the Wood River district galena- tetrahedrite veins cut through siliceous

limestone.

silver-gold

The Gold Hunter deposit

of silver base metal

ores occurs in quartzite.

Nevada During the year 1919 the largest output of silver, or about 3,535,000 oz., was produced in the Tonopah district, where the principal contributors were the Tonopah Extension, Tonopah Mining, Tonopah Belmont and West End. Large quantities of silver also came from the Nevada Wonder, in Churchill County, and the Rochester mines, in Humboldt County. Smaller outputs came from the Yellow Pine, Nevada Packard, Prince Consolidated, Elko Prince, and several properties at Virginia City. The Corns tock district produced about 240,000 oz., and several properties at Rochester produced about 575,000 oz. In 1918 dry or siliceous ores yielded all but 848,223 oz. of the output of silver, and nearly 88% of this

was recovered by cyanidation. The silver-bearing lodes at Tonopah occur

yield

in a series of

Tertiary eruptive rocks. There are younger lodes containing silver minerals in a quartz gangue traversing rhyolite-dacite,

and there are older lodes found

in

andesite.

This latter

set of lodes contains argentite, polybasite, stephanite, etc.,

UNITED STATES with some chalcopyrite, pyrite, and a

little

119

galena and blende

The country gangue consisting principally of quartz. rock in the neighbourhood of the lodes is greatly propylitized. The famous Comstock lode, in the Washoe district, is situated in a

The chief veinprincipally in propylitized augite-andesite. stone is quartz, and the metalliferous contents were concentrated in a series of large bonanzas. The most important silver these bonanzas were argentite, stephanite and

minerals of

Mining operations were suspended in argentiferous galena. Since then, except for a little sporadic work, the mines 1892.

have been idle. The main ore-bodies

in the

Eureka

district are

due to

re-

placement of a limestone along its faulted plane of contact with impervious quartzite. The primary ore consists of galena associated with pyrite. Within the oxidation zone these give place to various carbonates, sulphates, arsenates, molyb-

denates and chlorides, which are rich in gold.

Colorado

In 1918 there was an increase of silver contents in ore marketed direct from the mines, the decrease in silver and lead being due to a decrease in lead concentrate from leadLake County, chiefly Leadville, but including zinc ores. Lackawanna Gulch, Sugar Loaf, St. Kevin, and Wortman lode districts, and the Arkansas River dredge district, produced 2,348,000 oz. of silver. San Miguel mills, treating ore from both San Miguel and Ouray counties, produced 1,170,000 oz.

Owing to various difficulties connected with labour, was a falling off in the production of the San Juan Dolores County also showed a small decrease, but region. in Mineral County there was an increase of over 100 %. Decreases are recorded from Cripple Creek and Boulder and Chaffee of silver. etc.,

there

Pitkin County (Aspen) yielded 570,000 oz. of silver. In 1918 siliceous and dry ores yielded 67% of the silver recovered, lead ores 21%, lead- zinc ores 8%, and copper counties.

ores

2%.

The remainder came from

placers, zinc ores

copper-lead ores. The silver-lead occurrence at Leadville represents

9

and

a meta-

SOURCES OF SUPPLY OF SILVER ORES

120

somatic deposit in blue- grey dolomitic limestone, of Carboniferous age. The ore-bodies occur chiefly as flats at the junction of the limestone and microgranite. The ores are mostly

made up of The deposits

anglesite, cerussite, galena and pyromorphite. at Aspen are also of the replacement type in

limestone.

In the Cripple Creek district a series of related Tertiary intrusive rocks occur in pre-Cambrian granite and slate. The lodes occur principally in breccia and phonolite, but to some extent also in other rocks. Considerable alteration of the

country rock in the neighbourhood of the veins has taken place.

The

ore consists of tellurides of gold, silver and lead, and and small amounts

In addition, tetrahedrite, stibnite, pyrite. of galena, blende, molybdenite, etc., occur. sists of quartz, fluorspar

The gangue

con-

and dolomite.

Fissure veins connected with intrusive rocks occur at Clear Creek, and also in Park, Gunnison and other counties. Fissure veins contained in volcanic surface flows occur in Mineral

County (Creede), and Ouray and San Juan

also in

San Miguel, Custer, Hinsdale,

counties.

Arizona

A large from a

decrease in output was recorded for 1919 resulting falling off in shipments of lead ore, which contains

considerable amounts of silver.

Of

the 6,686,152 oz.

of

1918, 5,347,618 oz. came from copper from dry or siliceous ores, 362,182 oz. from lead ores, 36,208 oz. from lead- zinc ores, and smaller quantiCochise ties from zinc, copper-zinc and copper-lead ores. came oz. of which County produced 2,315,518 oz., 1,693,598 from copper ores and 426,019 oz. from siliceous ores. Yavapai County produced 2,502,968 oz., mainly derived from copper Bullion recovered from gold and silver ores, almost ores.

silver

produced

in

ores, 913,973 oz.

by cyanidation, yielded 158,476 oz. of silver. Concentrate contained 1,119,510 oz., and crude ore shipped to smelters contained 5,372,505 oz., or more than 80% of the total output

all

of silver.

The

silver

base metal ores are derived from imperfectly-

UNITED STATES

121

known

districts in Gila, Mohave, and Santa Cruz counties, in part probably represent oxidized and enriched ores. In 1906 the largest part of the siliceous silver- lead- copper

and

ores produced in Arizona was contributed by the Tombstone mine, working veins and replacements in limestone, quartzite, and shale near bodies of intrusive rocks.

The

siliceous

silver-gold

ores

are

derived

from

fissure

veins in volcanic flows, principally rhyolite or dacite, and the larger part of it comes from Cochise County.

The

siliceous silver ores seem to be largely oxidized ores from veins connected with intrusive rocks, in the Cerbat Range, Mohave County, also from Globe, and from mining districts in

Yavapai County.

California

In 1919 the silver was derived mainly from copper and lead ores, although an appreciable quantity was also mined with the gold. Owing to the rise in the value of the metal

some few old

silver mines in the southern part of the State have been reopened, but none on any large scale. In 1918 more than 47% of the output, or 669,711 oz., came from copper ores. Zinc and silver-lead ores yielded 499,759 oz., siliceous ores 228,332 oz., and placers the remainder. The only counties producing more than 100,000 oz. of silver in of all the 1918 were Shasta, Inyo and Plumas. About 69 silver was recovered from crude ores sent to smelters.

%

Alaska In 1918 the copper mines produced 719,391

oz., siliceous

ores yielded 90,064 oz., and the placers 38,334 oz., out of a total of 847,789 fine oz. silver.

New Mexico The Fanney cyanidation

mill

and the Ernestine

mill,

both

at Mogollon, yield the bulk of silver produced in New Mexico. In 1918 the total output amounted to 782,421 oz., of which

Socorro County produced 352,878 fine

oz.,

or

45%,

chiefly

122

SOURCES OF SUPPLY OF SILVER ORES

from siliceous ores from the Mogollon district, the remainder from mixed ores of the Magdalena district. The output from Grant County amounted to 338,833 oz., and most of this yield came from the Lordsburg and Central districts. Dry and siliceous gold and silver ores, chiefly from Grant and

%

of the total Socorro counties, yielded 48 copper ores, Socorro and from Santa Fe counties, yielded Grant, chiefly 32%. The remainder of the production was from lead-zinc ;

and copper-lead ores, mainly from the Central, Cook's Peak, and Magdalena districts.

Victoria,

The Mogollon deposits belong to the second type recognized by Lindgren and are associated with volcanic flows. Texas

The greater part

of the silver

mine and cyanidation

mill

in

comes from the Presidio

silver

the Shafter district, Presidio

County.

Michigan In 1918 the copper mines at Michigan produced 509,067 The silver was mainly derived from the of silver. of 56,127,000 Ib. of copper. The average treatment electrolytic " 0-18 oz. of rock" treated was ton of silver per recovery Of the total output of silver, 453,957 oz. came from mines in fine oz.

Houghton County. The ore consists of native copper amygdaloid and conglomerate gangue.

in

an

Washington In 1918 about half the silver came from copper ores, and most of the remainder from Republic ores. In 1918 Ferry County produced 101,376 oz., mainly from siliceous ores, and Stevens County 168,669 oz., mainly from copper ores, out of a total of 310,093 oz.

South Dakota

South Dakota, which was mainly derived from refining gold bullion, was 159,202 oz.

The output

of silver in 1918 in

UNITED STATES

123

124

O

3 $

^

en

& I

SOURCES OF SUPPLY OF SILVER ORES

UNITED STATES

2

-0

<$

a -

cq

125

126

SOURCES OF SUPPLY OF SILVER ORES Oregon

In 1918 the total output in Oregon was 107,323 fine

which 77,031 oz. came from siliceous ores, 26,161 copper ores, and 4,102 oz. from placer bullion.

oz.

oz., of

from

Southern Appalachian States

These include Alabama, Georgia, Maryland, North Carolina, South Carolina, Tennessee and Virginia. In 1918 the total production of silver in Tennessee and Virginia was 95,478 oz. Only 44 oz. came from siliceous ores and placers, and 95,434 oz. from copper ores.

Wyoming Silver is obtained

partly from the siliceous ores of the

Seminole and Elk Mountain

districts, in

Carbon County.

SOUTH AMERICA BOLIVIA

was discovered in the Potosi Mountain in 1544 [95]. The mountain consists of a cone of porphyritic These rhyolite surrounded by conglomerates, shales and tuffs. Potosi.

Silver

rocks are traversed

by hundreds

of approximately parallel

veins and the intervening country rock is considerably mineralIn the oxidized zone the silver occurs as cerargyrite ized.

and native metal, whilst within the sulphide zone the upper portion is characterized by an abundance of pyrargyrite and at lower levels by tetrahedrite. Cassiterite is also to be included as one of the constituents. Pyrite is practically the only gangue, although small amounts of barytes and quartz are present.

The Bolivian output of silver from 1553 to 1910 is said to have been 48,800 tons, of which the mines of Potosi are stated to have contributed no less than 30,000 tons. At and Bolivia Chile about tons annum. 125 yield present per A large part of this comes as a by-product from the tin mines, whilst another part is derived from the mine near Huanchaca.

BOLIVIA The great mineral tains

CHILE

belt of Bolivia lies in the chain of

127

moun-

which forms the eastern border of the high plateau of

that country, a region of Palaeozoic folded slates with cores diorite and granite, together with porphyritic intrusions.

of

The characteristic ore-bodies flows are generally absent. are those containing both silver and tin. The most important districts are Carabuco, Avicaya, Milluni and Huayna-Potosi, Lava

Monte Blanco in the Quimza-Cruz mountains, Colquiri, Oruro, and Huanuni, Llallagua, Colquechaca, Potosi,

Morococha,

Porco, Pulacayo, Huanchaca, Chocaya, Tasna, Chorolque, etc. The primary silver minerals are principally antimonial tetrahedrite, terite

with pyrargyrite, proustite and stephanite.

and a large variety

of other minerals also occur.

Cassi-

The

most important gangue-mineral is quartz, which is occasionally accompanied by some calcite and barytes. The upper parts of these lodes carry native silver, cerargyrite,

The wonderfully rich silver veins pyrargyrite, proustite, etc. of Potosi change in depth to pyritic tin-bearing veins. At Corocoro extensive deposits of native copper, with some native silver, domeykite, certain silver ores, etc., occur as an impregnation in sandstone. CHILE Mineral deposits of commercial value are practically confined Here the Jurassic and Cretaceous formato northern Chile. tions

are

flows

developed with contemporaneous lava volume. Into these are intruded granite

strongly

of great porphyries and diorite porphyries in smaller stocks, as well as many batholithic masses of granodioritic rocks. The great majority of mineral deposits are associated with these intrusives,

flows.

although a certain number occur in late Tertiary lava Moricke classifies those ore-deposits containing silver

into the following groups

:

I. Silver-copper deposits. Deposits containing argentiferous copper ores in basic plagioclase-augite rocks or in Mesozoic sediments, especially limestones, penetrated by the igneous The chief gangue-minerals are calcite, barytes and rocks. Deposits containing silver, but with only a subordinate quartz.

amount

of copper,

occur at Tres Puntas, Cabeza de Vaca,

128

SOURCES OF SUPPLY OF SILVER ORES

Los Bordos, Chanarcillo, San Antonio in Atacama, Algodones, Rodeito, Argueros, Quitana in Coquimbo, etc. II. Silver lodes with a high gold content. These occur in both basic and acid igneous rocks. Free gold as well as silver chlorides occur, e.g. at Lomas Bayas in Atacama, and Condoriaco in Coquimbo. III. Deposits containing galena, blende, tetrahedrite, enargite,

Examples of such argentiferous deposits occur at Cerro Blanco and La Coipa in Atacama, Las Hediondas, Vacas Heladas and Rio Seco in Coquimbo. etc.

The

principal silver-bearing provinces are in the northern portion of Chile. Proceeding from north to south they are

as follow

:

Tarapacd.

The Huantajaya mines,

east of Iquique, are

yielded an enormous

amongst

in the Coast Mountains, the oldest in Chile and have

amount

of high-grade ore. The formation metamorphosed limestone and schist. The veins are productive only in the limestone, and carry abundant native silver, cerargyrite and embolite. The new mineral huantajayite (approximately 2oNaCl -f AgCl) was found in

consists of

the partly-cemented superficial debris. In the Cordillera, east of the Pampa of Tamarugal, are various veins which carry argentiferous galena and blende

At Mina there are veins which carry and 2 dwt. gold per ton. They occur intruded by porphyry, gabbro and basalt dykes

in a quartz gangue. about 8 oz. silver

in diorite

(99/pp. 274-6].

The Caracoles

silver district, in the

department most important in this province. It was and was extensively worked for some years. Black marls of Jurassic age, dipping. south, have been intruded by dykes of quartz-porphyry and diorite-porphyry. Masses The main of porphyry also occur in the sedimentary rocks. lode (Resurrection) strikes N.-S. and can be traced for 2 km. The thickness varies from 2 to 6 m., and the filling at and near the surface consists of barytes with some calcite and iron oxide. At a depth of 50 m. the first bunch or shoot of ore was found, several metres in length and height and with a pitch to the south. Where the shoot occurred the country was more Antofagasta.

of El Loa, is the discovered in 1870,

CHILE

129

compact and of darker colour than nearer the surface, and there were numerous cross- veins. A second ore-body was discovered at a depth of 100 m. which was 90 m. in length and 15 m. in A series of veins formed a junction with the main height. vein at this point. The metalliferous minerals met with included native silver in wire form, proustite, pyrargyrite, cerargyrite, argentite, highly argentiferous galena and pyrite. The gangue consisted of calcite, barytes and altered country.

The average silver content was about 320 oz. per ton. At a depth of 137 to 155 m., a number of pockets of ore were met with, all pitching south, containing native silver, ruby silver, argentite, cerargyrite and iodyrite in a gangue of calcite, barytes and country rock altered through silicification, etc. Nodules of sulph-arsenide of silver and iron were found above the pockets, and masses of porphyry were also met with, in which argentite predominated in leaves or was disseminated The total depth reached was 200 m. The mines therein. are no longer being worked [100], They produced in the best years 120 tons of silver.

At El

Inca, 32

silver chlorides to

km. north

of Calama, are veins which carry in others, argentiferous ;

a depth of 152 m.

the principal ore. At Guanaco, 129 km. N.E. of Taltal, are gold mines, which carry some silver in enargite, and other copper ores. Below 121 m. the gold and silver contents

galena

became

is

negligible,

and the mines were worked

for copper

[99/p. 276].

The department of Copiapo is especially rich The famous mines of Chafiarcillo were discovered in 1831 or 1832, and for half a century produced a The isolated mountain of Chafiarcillo large quantity of silver. lies about 80 km. inland from the Pacific, between the ports of Taltal and Chafiaral, and has an altitude of 1,220 m. The formation consists of a bluish limestone of Jurassic age interstratified with various intrusive or highly metamorphosed Four beds of limestone, known as the first, second, rocks. third and fourth limestones, and three beds of oli vine-basalt or " dolerite, known as the first, second and third greenstones," Atacama.

in silver mines.

have been penetrated by the mine workings. Several layers in the limestone (termed sheets of porphyrite

SOURCES OF SUPPLY OF SILVER ORES

130

by F. Moesta) are impregnated with known as the Manto de Ossa, which

ore [101]

thus the one

;

really forms the roof of No. i limestone in the northern parts of the Colorado mine, is from i to 6m. in thickness, and has a vesicular structure, and, especially where calcite and limonite abound, the rock was found to be impregnated with granules, filigrees, leaves, plates and veins of native silver, mixed with argentite, cerarAbout 55 m. below this, a thin gyrite and some embolite. " " band of ferruginous limestone (? porphyrite), a few inches had small cavities encrusted with embolite, and thick, many filled

with calcareous clay [102].

The

sterile

according to

rock,

interstratified

Hen wood

Echegarai

them

A

the

limestone,

is,

largely of felspar,

composed more recent writer

[iO2/p. 79],

quartz and hornblende. calls

with

Nicomedes

sheets of melaphyre (altered olivine-

At Colorado a pair of parallel dykes basalt) and dolerite [103]. of augite-porphyrite, striking N.W. and dipping N.E., traverse all

the strata.

The

principal lodes strike N.E. metalliferous only in the limestone.

and dip N.W., and are

According to M. H. Gray, S.E., and, although many of them have been a to considerable explored depth, they have, generally speaking, been found to give unsatisfactory results [12]. Deeper still, the proportions of blende, galena and arsenopyrite increase. Calcite is the principal gangue in the limestone, with brownspar The lodes were richest (a variety of dolomite) and barytes. where they united with minute veins (cruceros) oblique both

some lodes dip

in direction

and

dip.

When Henwood

wrote his memoir, the workings on the Colorado lode were at a vertical depth of 414 m., and in the third bed of limestone. Since then the bottom levels of the Delirio and Constancia mines penetrated a fourth bed of limestone, in which the ore in the veins of high grade [104]. Portions of all the lodes

about 180 m. deep in the

was abundant but not

have been enormously first

rich, e.g. at

limestone, the Candelaria lode

for a length of 64 m. averaged upwards of 720 oz. silver The rich bunches pitched uniformly S.W., but per ton.

they were of course generally surrounded by

much

larger

CHILE

131

In 25 years, ending 1856, the principal bodies of inferior ore. mines of Chafiarcillo have produced silver to the value approximately of 6,140,000 [i02/p. 124], and from 1830 to 1853, or in 23 J years, the production of the department of Copiapo alone amounted to upwards of 1,100 metric tons of silver [I02/p. 153]-

Kenwood, referring to the lower grade ore, says "Of this there remains, either still unbroken in the lodes or rejected at " Echethe surface, almost incalculable quantities [i02/p. 93]. :

garai points out that the Descubridora lode is completely virgin in the third zone, having been exploited only in the first and second zones for a length of ij km. The suspension of is said to have been solely due to the abundance of water met with in depth. The above statements, provided they are correct, would appear to warrant the reopening of some of the old mines of Chafiarcillo. In the department of Vallenar several rich veins containing much native silver and some gold and copper were discovered

the deeper mines

in the beginning of the last century.

In the Vicuna

district,

104 km. east of Chanaral, quartz

and lead in syenite and porphyry [99/p. 277]. At present the silver production of the Atacama province comes mainly from the Elisa de los Bordos mine. veins carry argentiferous ores of copper

Coquimbo. Numerous very rich silver mines were formerly worked in the department of La Serena, but the richest ores are exhausted, and the mines are practically all idle now. The Arqueros deposits were discovered in 1825. The formation consists of Jurassic limestones traversed by porThe filling of the lodes comprises native amalgam, phyries. native silver,

pyrargyrite, cerargyrite, stephanite, tetrahedrite, bornite and chalcopyrite [i2/p. 875].

The Rodeito

silver

smaltite,

mines have also been highly productive,

as well as those of the Algodones district of the department of El Qui [99/p. 278].

According to Alberto Herrmann, silver ore was first discovered and worked in Chile in 1692, and from that time to the end of 1902 the country has produced 8,824 metric tons of metal [105].

132

SOURCES OF SUPPLY OF SILVER ORES COLOMBIA

Silver ores proper occur principally in the

departments of and Cauca Tolima, Antioquia. In the first, the Frias mines of Guayabal are the only ones at present being worked for silver alone. The Frias veins contain no gold. The silver ores occur along the line of intersection of two veins, which meet at an angle of 57 on

The country

is hornblende-schist. The and native silver with abundant ruby blende and galena. The gangue is quartz

the line of strike. ores are argentite,

silver

a little with some carbonate of lime. South of Guayabal are the Libano and Venadillo mines. The ores are principally gold-bearing, but contain from 3 to upwards of 20 oz. of silver to the ton.

pyrite,

In the Mariquita district, several old silver mines are found, which were formerly worked by the Spaniards, viz. Bocaneme, which has an E.-W. vein at the contact of andesite and schist, the ores being argentite and ruby silver, and Plata Vieja with an E.-W. nearly vertical vein, 60 cm. thick, of pyritic quartz, carrying

ruby

silver and, occasionally, native

The Santa Ana mine of the Santa Ana district was also formerly worked by the Spaniards, and was reopened about sixty years ago, but was abandoned in 1874. The vein Both gold strikes N.ioE. in schist, and is nearly vertical. and silver occur in pyrite, blende and galena. The Calamonte mine is in schist. The ores are pyrite and blende, occasionally The gangue is quartz. The rich in silver, and native silver.

silver.

vein also carries gold. In the Marmato district of the department of Cauca, several In the Marmato gold mines the ores silver veins are known.

carry from 10 to 20 oz. of silver per ton. In the Echandia district, a few km. south of Marmato, vertical veins from 30 to 150 cm. thick occur in hard rhyolite near schist, and close to

a dyke of

diorite.

The

ores are pyrite, galena, blende, chalco-

pyrite, arsenopyrite, native silver

and

gold.

The gangue

is

quartz and calcite. In 1900 the annual production of Echandia was 230,000 oz. of silver and 2,000 oz. of gold [g6/p. 123]. In Antioquia, Caramanta is the only district which is princi-

COLOMBIA PERU

133

An E.-W. vein occurs in a porphyritic The ores are galena, blende, tetrahedrite, The gangue argentite, ruby silver and native silver (scarce). Some free gold is found at and near the surface. is quartz. In Manizales, the Diamante mine has a lode from 91 to 122 cm. thick of soft breccia, composed of trachyte and rhyolite,

pally argentiferous. " rock near trap."

and traversed by small quartz veinlets 1-25 to 4 cm. thick, carrying free gold, auriferous pyrite, argentite and a little

With increasing depth the tenor of the lode in chalcopyrite. silver increases greatly [6g/p. 622]. In Volcanes, a vein in mica-schist strikes N.-S., dips W. is 60 cm. thick. It shows native gold with tetrahedrite and ruby silver. In Morisca the country is (freibergite) and the rhyolite, gold is associated with dark ruby silver and

and

brogniartite [96/p. 142].

The famous Zancudo mine, near at

the

junction

of

Titiribi, is

a contact vein

hornblende- schist with

overlying consulphides are arseno-

glomerate, having diorite near. The pyrite, chalcopyrite, blende, galena, stibnite and dyscrasite, with some nickel, cobalt and manganese ores. The gangue is

quartz and calcite.

and 18

The

oz. of silver

The

ores average 17 dwt.

of gold,

per ton.

fineness of the bullion

from the important Remedios

gold district averages about 600 gold and 350 silver, and that of the vein-gold of the whole of Antioquia is said to average

698 gold and 302 silver, and that of the placer gold, 834 gold and 136 silver [97].

PERU Peru is the leading silver-producing country in South America, the greater part of the output being derived from the copper mines of Cerro de Pasco. A small amount comes from lead bullion, and the remainder from silver or gold- silver

The districts in which silver-bearing deposits occur are very numerous and are generally situated in the Western Cordillera in the departments of Cajamarca, Libertad, Ancachs,

deposits.

Huanuco, Junin (Cerro de Pasco), Lima, Huancavelica and Arequipa. In Peru and Chile, along the coast and Central Cordilleras,

SOURCES OF SUPPLY OF SILVER ORES

134

a strong development of Jurassic and also of Cretaceous sediments, folded and in part overturned towards the east. These Mesozoic sediments contain interbedded lava flows of the same age, which, however, do not appear to there

is

importance as regards mineralization. The great majority of Peruvian deposits are in close genetic connection with numerous intrusions of dioritic or monzonitic porphyries, probably of early Tertiary age. Thus the Cerro de Pasco deposits occur at or near the contact of an intrusion of a dioritic prophyry with the surrounding Cretaceous sediments. be

of

Formerly, the lodes carried very rich silver ores in their upper parts, but in depth these give place to low-grade copper ores. The production of silver in Peru during the year 1918 amounted to 9,781,733 oz., compared with 10,864,624 oz. in 1917.

The principal silver-bearing departments, proceeding from north to south, are as follow Cajamarca. In the district of Hualgayoc (altitude about 3,650 m.) in the province of the same name, silver-bearing veins proper are associated with andesite, and copper-bearing The primary veins, containing more or less silver, with diorite. ore of the latter is enargite. Cerro Jesus is the centre of the :

and contains four systems of veins striking N.67E., N.45E., N.8oE. and N.20W., of which the first is the most important. The filling consists of the common sulphides of copper, lead, zinc and iron, and native silver

mineralization,

silver, argentite, pyrargyrite, stromeyerite,

hedrite, enargite and calcite and barytes.

bournonite, tetra-

some native gold, in a gangue of quartz, The oxidized ores, now exhausted, were

rich in silver.

The Cerro

Chilete (altitude 1,340 m.), in the province of Cajamarca, is built up of diorites and amphibole porphyries. The sulphide zone Several veins traverse these rocks. consists of antimonial argentiferous galena and blende, in a gangue of quartz, but cerargyrite and native silver occur in

the oxidized zone.

At Sayapullo, in the province of Cajabamba, limestone, overlaid by sandstone and shale, strikes E.-W. and dips N.

The

veins, 125

cm. in thickness, striking N.W. and dipping

PERU 30

to

35

S.W., contain argentite,

135 tetrahedrite,

enargite,

The filling of the chalcopyrite, pyrite, blende and quartz. veins at Algamarca is similar, but enargite and blende appear The veins strike N.E. and dip 60 to 70 S.W. to be absent. in shales arfd quartzite.

They

are from 80 to 120 cm. in

thickness [99/pp. 447-9]. In other districts of the department silver occurs in lead or copper ores, or in both, and although, in many instances, silver ores may occur in the oxidized zone (forming pacos), they are more or less rare in the sulphide zone.

In 1917 the province of Cajabamba produced 100,200 oz. of copper ingots, and the province of Hualgayoc from leached sulphides. oz. yielded 116,800

silver contained in

Libertad.In the

province of Santiago de Chuco, copper ores enargite, tennantite and tetrahedrite predominate, and contain under 16 oz. silver per ton, but the district of Quiruvilca,

veins of Llacapuquio are rich in silver (800 to 1,000 oz. per metric ton), and carry only 4 or 5% of copper. It is noteworthy that red blende in small crystals and barytes generally

accompany the shoots

of ore rich in silver,

and that when

the copper content increases, the silver content diminishes, and vice versa.

Enargite when pure carries 45 -5% copper and

ii oz. silver per metric ton [106].

In the Aguinuay district the country is augite-andesite, and the ores are galena and blende with spots of tetrahedrite At San Miguel the ores are similar, with the rich in silver. addition of bournonite, rich in silver and at Santa Rosa the sulphide region is characterized by argentiferous and ferriferous jamesonite with much pyrite and spots of tetraBlende is rare. At Mundo Nuevo, when slate forms hedrite. the country, argentiferous lead and zinc ores predominate, ;

but when it is quartzite, copper ores prevail [107]. In 1917 the province of Otuzco yielded 129,100 oz. of silver from silver ores, and the province of Santiago de Chuco, "La Guardia " mine in 51,000 oz. silver from lead ores. Otuzco produced ores very rich in gold and silver. Ancachs. In the Macate district, province of Huaylas, both lodes and bedded- veins (mantos) occur in shale and sandstone intruded by mica-diorite. 10

The minerals

are

native silver

136

SOURCES OF SUPPLY OF SILVER ORES

small quantity), argentite, pyrargyrite, tetrahedrite, galena pyrite, and their oxidation products, in a gangue of quartz. The ore of these districts is also essentially argentiferous (in

and

galena, including, in addition to the minerals already mentioned, chalcopyrite, blende, bournonite and siderite. Recuay is the most important district of the province of

Huaraz. The Anglo-French Ticapampa Co., Ltd., owns mines in Collaracra. There are two mineralized zones, one of galena and one of complex sulphides, with a high silver content and some copper. The former diminishes, and the latter increases in depth.

The production amounted

to 591,000 oz.

silver in 1917.

In the San Luis and Chacas the formation

is

quartz- diorite,

district,

province of Huari,

upon which

rests in succession

metamorphosed black shale, sandstone and coalThe veins strike N.W., N. or N.E. The bearing strata. order of abundance, are galena, blende, stibnite, in minerals, contact

pyrite, chalcopyrite, tetrahedrite

and some stephanite, poly-

bournonite and arsenopyrite. The blende contains from 20 to 45 oz. silver, and the leanest galena over 90 oz.

basite,

silver per ton.

At Tulla, three veins, coursing N.-S. and dipping W.53, are cut by a vein striking E.-W. and dipping 5.45. The country is slate and gneiss cut by igneous rocks. The thickness varies from o to 120 cm., and the average ore contains from 40 to 60 oz. silver per ton. The ore consists of galena, blende, auriferous pyrite, with small amounts of tetrahedrite, ruby silver and native silver, in a gangue of quartz, calcite, siderite

and fragments of wall-rock. In the Auquimarca district, of the province of Cajatambo, The veins, 2 m. in thickness, are found in dioritic country. filling consists of native silver in threads and dendritic forms in quartz, tetrahedrite, galena, chalcopyrite and pyrite, and the In the Quichas ore contains from 130 to 550 oz. silver per ton. The ore district the formation is limestone and sandstone. is tetrahedrite with pyrargyrite, realgar and pyrolusite in a gangue of calcite and grossularite, and averages 70 oz. silver per ton. Pure tetrahedrite has as much as 900 oz. silver per ton. The ore in the Socorro mine, in the Chanca

PERU district, is

banded

;

137

the successive layers from the centre to

and calcite, sprinkled with pyrargyrite and tetrahedrite, fine and coarse pyrite, thin bands of quartz and calcite, and thick bands of pyrite. Galena, blende and the walls are quartz

chalcopyrite also occur [99/pp. 451-4]The ores of the province of Pallasca are characterized by high silver content as compared with their lead and copper contents.

Tetrahedrite in Ancachs generally carries tin [108]. In 1917 the department produced 743,300 oz. of silver.

Huanuco. A silver- copper-lead belt traverses the province Dos de Mayo. The ores of the Huallanca district consist principally of argentiferous pyrite and tetrahedrite in a quartz gangue. In the Chonta district are three bedded veins (mantos) inters tratified in sandstone and quartzite, consisting of pyrite, blende, galena, cinnabar and tetrahedrite, which were formerly worked for the mercury content [99/p. 454]. of

,

All the silver in this department from the treatment of copper ores.

is

extracted as a by-product

Junin. The silver- lead- copper deposits of this department occur in a belt less than 50 km. wide in its western part. The

northern half of the zone includes the well-known districts of Cerro de Pasco, Colquijirca and Morococha.

The Cerro de Pasco district, in the province of the same name, was discovered in 1630, and has produced a large quantity of oxidized ores, or pacos, containing silver, but, since 1898

it

has been worked mainly for copper. The country consists There has principally of rhyolite agglomerates and tuffs. been a concentration of silver and a leaching of copper in the oxidized zone. Low-grade pyritic ores occur below this zone, but, here and there, are portions so enriched with enargite and famatinite that they can be worked at a profit. The copper ores contain silver. In the Colquijirca district of the same province, there are two beds of ore intercalated in the limestone series, which In some places the manto consists represent replacements. almost wholly of chert, and in others almost entirely of pyrite.

Galena and barytes are present when the deposit is richest in silver, with, here and there, a little chalcopyrite and tetrahedrite.

Magnificent specimens of native silver in wire-form

SOURCES OF SUPPLY OF SILVER ORES

138

occur in the oxidized or partially oxidized ores. Its most common habitat is in the spaces between the interlocking tabular crystals of barytes, where it may be found alone or adhering to some of the sulphides, very commonly to the tetrahedrite.

In the Vinchos district, north of Cerro de Pasco, there are veins in limestone, which has been intruded

The

filling consists of

by igneous

rock.

galena, pyrite, arsenopyrite, chalcopyrite,

The tetrahedrite, bournonite, pyrargyrite and native silver. silver content varies from 70 to 300 oz. per ton, and the lead from 25 to 30%. The thickness of the veins varies from 20 to 50 cm. There are ore-shoots at the intersections.

In the Huaillay (sometimes called Huancavelica) district, south of Colquijirca, veins in micaceous dacite yield enargite and tennantite in quartz. In the sedimentary rocks (Cretaceoussandstones and marls metamorphosed in contact with dacite) there is less copper and more lead and zinc in the ore, and the gangue is more calcareous than in the eruptive Jurassic

rocks.

In the Morococha

district,

province of Yauli, the formation

argentiferous copper porphyry and peridotite being worked and are yielding a large output of copper and silver, but silver-lead ores also occur in the district they are not being mined at present [99/pp. 454~5 and On the Cerro San Marcelo, sulphides and complex 476-8]. consists of

ores are

;

now

;

sulphides of silver (pavonados) with oxidized ores (pacos) occur metamorphosed limestone, which appear to have

in veins in

favoured the precipitation of

silver, for

where the limestone

the silver present is very small in quantity. " " Flats occur, having a floor of highly siliceous limestone, and a roof which appears to be a friction-breccia. At Cerro

is little altered,

Alpamina, highly argentiferous galena, sometimes accompanied by oxidized or sulphide silver ores, occurs in the marls and limestone [109]. In the Yauli district, of the same province, native silver and argentite, with small quantities of blende, pyrite and

In depth galena, occur in the uppermost part of the veins. sternin to turn to this pyrargyrite argentite gives way ;

bergite, with native silver

becoming very

rare.

Galena, blende,

PERU

139

especially pyrite, show progressive increase in amount with depth. Still lower are geodes with small amounts of native

and

silver, pyrite first becomes cupriferous and argentite again appears, followed by tetrahedrite and the almost complete disappearance of the rich silver minerals [99/p. 455].

At Carahuacra, iron oxide occur in shoots. This region

is

is

very abundant, and rich ores to have a great future

deemed

At Andachagua, galena, iron oxide predominate. and blende

before

it.

tetrahedrite, native silver,

In 1917 the department of Junin produced 5,707,700 oz. 5,499,000 oz. of which resulted from the smelting of copper ores in the province of Cerro de Pasco, and 121,900

silver,

from lead ores produced in the province of Yauli. Lima. The Casapalca district is being worked for its The veins are for the most part argentiferous copper ores. in andesite. The San Antonio is the only mine in the district that contains ruby silver and gold in any quantity. In the Lircay district of the province of Huancavelica. Angaraes, pyrite, chalcopyrite, galena, occur in the country There are rock, with siderite, barytes and ocasionally quartz. three varieties of tetrahedrite in colour, with from (a) silvery 600 to 650 oz. silver and 5% copper (6) silvery-grey, found below this, with from 450 to 500 oz. silver and 15% copper, and (c) reddish, found at still greater depth, with from 300 to 400 oz. silver and 20% copper. The Acchilla vein runs N.W. and dips N.E. in dark porphyritic rock. The filling oz.

:

;

consists of galena, tetrahedrite, arsenopyrite, and much ruby silver and argentite. The ordinary ore contains 300 oz. silver

per ton. In the Vizcachas

region

(10

km. east

of

Lircay),

the

Vizcachas vein, 15 cm. in thickness, strikes N.-S. and dips

W.

in porphyritic rock. It contains native silver in plates filaments in a gangue of calcite and some quartz. Sulphides of copper and lead are accessory.

and

The

silver-lead-copper region of Huachocolpa (province

of

Huancavelica) and Carhuapata (province of Angaraes) is found in the porphyritic facies of the Mesozoic. In the famous Quespesisa mine, which lies at an altitude of 5,000 metres, galena and blende are the most abundant minerals, and they

SOURCES OF SUPPLY OF SILVER ORES

140

are

associated

with

native

silver,

pyrargyrite,

argentite,

proustite, stephanite, pyrite, chalcopyrite

and

The

stibnite.

is quartz, and some barytes. The Candalosa vein contains galena, blende, bournonite, chalcopyrite, pyrite, stibnite and tetrahedrite (with 5 dwt. gold per ton). There are three

gangue i

varieties of tetrahedrite in this

mine

:

crystallized, brilliant

(a)

silvery, with 270 oz. silver and 15% copper; (b) crystallized, steel- colour with blue and yellow shade, 200 oz. silver and 25% The (c) amorphous, 53 oz. silver and 30% copper. copper mine is in the zone of rich sulphides. Quespesisa has probably yielded three times more silver and gold than Candalosa, ;

although statistics are lacking, and is regarded by some as still being above the rich sulphide zone.

The

Nanantuyo, Sapralla and of Totoral Grande y Chico should also be mentioned, as argentiferous galena is the principal ore of each [no] [99/pp. 455-9]In 1917 the department produced about 32,000 oz. of silver-lead

regions

of

silver.

Cuzco.

Silver-bearing galena

and tetrahedrite occur

in veins

In the Vilcain the Lares district of the province of Calca. bamba district of the province of La Convencion, four systems of veins occur in sedimentary rocks (probably Carboniferous), having an intrusion of porphyry, with which the mineral

deposits no doubt bear

W.

some genetic

relation, viz.

:

(i)

N.-S.

;

argentiferous tetrahedrite, with argentite and native dip in calcite silver country metamorphosed limestone and red (2) N.-S. dip E. argentiferous galena porphyritic sandstone ;

;

;

and some tetrahedrite with dip

S.

;

the principal ore

is

;

calcite in limestone

;

(3)

niccolite (NiAs) in calcite,

E.-W.

;

accom-

and occasionally smaltite sometimes associated with pyrite, dip (4) N.E. argentiferous tetrahedrite, galena and arsenic with N.W. copper ores, argentiferous tetrahedrite as a rare

panied by gerdormte (CoAs 2). The niccolite

(NiAsS),

is

;

;

;

constituent. district, on the summit of the Eastern an altitude of 4,600 metres, the principal sulphides from the surface down, are pyrite, galena, blende and stibnite. The gangue is quartz, calcite and barytes, and the country a red porphyry which has been highly altered by

In the Chimboya

Cordillera, at

PERU The galena

propylitization. in silver.

is

141

usually fine-grained and rich

In the province of Paruro, there is a replacement vein of highly argentiferous galena in white quartzite. In the province of Chambivilcas, veins of argentiferous galena are found in patches of limestone, resting on a laccolite of quartzose diorite, and, in the Furgani region, the same mineral is found

which rests on limestone-conglomerate, which on quartz-diorite [in]. Apurimac. In the Challhuanca district of the province of Cotabambas, there are lodes at Pisti which carry pyrite, silver sulphides and iron oxides. The veins are in granite and are 0-5 m. in thickness. The sulphides of silver yield about 58 oz. silver per ton. North of Lake Tunicre (altitude 4,460 m.), there occurs a vein in quartzite, which consists of a number of stringers these occasionally unite and form a vein 0-3 m. in thickness. This vein carries silver sulphides in limestone

in its turn lies

;

[112].

The

silver

produced in

this

department

is

a by-product

of the gold industry.

Puno.

At Santa Lucia

(altitude 4,370 m.), in the province very irregular mineralizations occur in limestone.

of

Lampa, They sometimes

constitute large bunches, and sometimes appear may be regarded as impregnations or reThe deposits are rich in iron of limestone. the placements and manganese, and contain silver and copper, and, here

as

little veins,

and

and

pure polybasite occurs, containing 3,215 oz. per ton and 25% copper. Until a few years ago, the deposits were worked by the Lampa Mining Co., Ltd., which there,

silver

owned a 3o-ton per day

The future of the mine smelter. on of the the large ferruginous economic depends winning from 27 to 35 oz. with masses assaying 1-5 to 2% copper, silver per

ton [113].

In 1917, the province of

from copper

Lampa

yielded 72,800 oz. silver

ores.

The plateau region of southern Peru, west of Lake Titicaca, built up of Palaeozoic shales and limestone, Mesozoic and Tertiary sandstones and acid eruptive rocks. Silver-bearing is

lodes occur in the igneous rocks, and, to a lesser extent, in

SOURCES OF SUPPLY OF SILVER ORES

142

limestone. The silver lodes usually carry and a considerable amount of chalcopyrite, In general, the sulphides of copper, galena, blende and pyrite. iron and are lead zinc, present in roughly equal proportions, an difficult to treat. ore The gangue consists of forming rhodonite and The copper ores in the quartz. barytes, calcite, Tertiary sandstones contain, as a rule, much smaller amounts

the

a

of

Palaeozoic

little

gold,

than

silver

when they occur

in

the

Palaeozoic

sedi-

ment aries. Arequipa. In the Quequena and Cerro Verde mining regions numerous copper-bearing veins occur in diorite and carry some silver [113]. The first silver mines of the Caylloma district (altitude 5,000 metres), in the province of the same name, were worked

by the Spaniards in 1630, and, prior to that time, by the Incas. The veins occur in andesite, and contain pyrargyrite, argentite and native silver, which, in depth, are largely replaced by polybasite and argentiferous galena. Tetrahedrite, rich in silver, occurs occasionally, and blende, pyrite and chalcoThe gangue is rhodonite and quartz pyrite are also present. with a little calcite and occasionally rhodochrosite, barytes Even the purest samples of rhodonite and or wavellite. quartz have yielded from ij to 3 oz. silver per metric ton. The outcrop of the principal vein now worked is traceable for nearly 4,000 m. From 1890 to 1905 the Caylloma Silver Mining Co., Ltd.,

(Chilian)

Caylloma

In 1906 a oz. of silver. Consolidada Sociedad Explotadora was formed. Its monthly output averages

produced 5,542,000

company

new de

no

tons of concentrate assaying 190 to 280 oz. silver per ton, together with gold and lead [114] [115].

In 1917 the province of Caylloma yielded 225,000 oz. silver silver ores, etc., and the output of the province of Arequipa amounted to 13,300 oz. silver from copper ores. Practically the whole of the production came from the mines owned by the Caylloma company [113]. The tables on page 143 give productions of silver in Peru classified according to the nature of the products and as regards

from

the outputs of the departments respectively. The nature of the products which carry

silver,

together

PERU

1

COO

u-)O

M N

1000

T- r-

oco

N

o

o N

ON

CO Tf CO

04

1

1

rj-

43

-<J-

O OONO

-^ *o

0<

OCO NM

M

O

fO ON CO iO

N t-^

N

M" rf 10 of

O

CO CO

OON

ON

04

COO

M CO

CO s I -

rt- -<1-00

CO CO

^
O 00 OOO 10 00 COO O 00 O 00 O ^ M

Tf-

oO ON

M M 00 o o o 10 M ON TJ- 04

V>

oo" oo"

o" rh

i>,

00

OONOOM 04

ON

Tf CO M ON **" >O O -^- CO

of of coo~oo"

O 00^ >OOO IO M C^

O

CO

ON o" 04

00

04

s-

I

ON

M M M M

o" >O co

CO

04

CO

COO

04

oo o r- o MOO

M

ON 0^

co of ON M" ON

O

ONOO

O O

Annua

f 10

M 00

eg"

O

rt- 04

O

>O ON 04

COO

04

>O

$<$& S

CO ^-

>OO

s-

I

ON ON O> ON ON

144

SOURCES OF SUPPLY OF SILVER ORES

with the amounts of stiver contained in these products,

summarized as follows Nature

:

of Silver-bearing

Products and their Content in

Silver,

1917

is

REFERENCES TO LITERATURE ON SILVER The Publications [i]

[2]

are referred to by

Numerals in

Mineral Industry, 1919, 28. " Gold and Silver in 1918," U.S.

the Text.

Geol. Surv.,

U.S., 1918. Presidential Address, Trans. Inst. [3] McNeill, B. :

Min. Res. of

Min. and Met.,

1913, 22. [4]

[5]

Barbour, D.

Abstract of Proceedings of Council of GovernorGeneral of India, June 26, 1893. A Dictionary of Applied Chemistry, London, Thorpe, E. :

1913, [6] [7] [8]

:

4.

,

Encyclopedia Britannica, 22. Encyclopedia Britannica, 18. Simpson, E. S., and Gibson,

C.

G.

"

Geology and Ore De-

:

posits of Kalgoorlie," pt. i, Geol. Surv. Bull. 42.

Carpenter, H. C. H., and Cullis, C. G.

W.

Australia, 1912,

"

Report on World's Production of Silver," Rept. of Comm. ... on Indian Exchange and Currency, 1920, 3, Append, xxx. Ore Deposits (Trans, by S. J. [10] Beyschlag, Vogt, and Krusch Truscott), 1, 1914; 2, 1916. [u] Mines and Quarries : General Report and Statistics. A Treatise on Ore Deposits, London, [12] Phillips, J. A. (H. Louis) [9]

:

:

:

1896. [13] Records of Geol. Surv.

,

India.

[14] Bd. of Trade Journ., Nov. 13, 1919, p. 595. [15] Annual Report of Rhodesia Chamber of Mines, Bulawayo. " [16] Wagner, G. P. A. Geology of Portions of Pretoria and :

Middelburg Districts," Transvaal Mines Dept. 1907. [17]

[18] [19]

"

Geol. Surv.,

Wagner, G. P. A. Geology and Mineral Industry Africa," Union S. Africa Geol. Surv., 1916, Mem. 7. Annual Reports on Min. Production of Canada. Trade and Commerce Reports of Canada. :

of S. W.

148 [20]

REFERENCES TO LITERATURE ON SILVER "

Lewis, S. J.

Ore Deposits of Mexico VI. Ore Deposits Flows of Igneous Rock," Min. and Sci. Press,

:

in Surficial

Oct. [21] [22]

9,

:

[24]

Summary Summary

[25]

Lewis,

[23]

1920.

Annual Reports of Min. of Mines of Brit. Columbia. " Ymir Mining Camp, B.C.," Drysdale, C. W. Canada, 1917, Memoir 94.

Report of Geol. Surv., Dept. of Mines, Canada, 1916. Report of Geol. Surv., Dept. of Mines, Canada, 1915. "

S.

J.

Deposits

June [26]

[27]

Ore Deposits of Mexico III. Non-Contact Sedimentary Rocks," Min. and Sci. Press,

:

in

26, 1920, pp. 934-5-

"

Ore Deposits of Mexico V. Ore Deposits in Igneous Rocks," Min. and Sci. Press, Sept. n, 1920, p. 383 " Texada Island, B.C.," Geol Surv. Canada, McConnell, R. G. Lewis, S.

J.

:

:

1914,

Mem.

58.

W.

"

Geology and Ore Deposits of Rossland, B.C.," Geol. Surv. Canada, 1915, Mem. 77. [29] Annual Reports of Ontario Bureau of Mines. " Economic Minerals and Mining Industries of Canada," [30] [28] Drysdale, C.

'

Geol. Surv.

[31]

Mines Branch, Dept. Mines, Canada, 1913, No. 230, p. 32. " The Onaping Map- Area," Geol. Surv. Canada, Collins, W. H. :

1917,

[34]

[35]

Mem.

H. F.

95.

Types of Ore Deposits, 1911, pp. 140-56. " Collins, W. H. Geology of Gowganda Mining Division," Geol. Surv. Canada, 1913, Mem. 33, p. 26. Annual Reports of Dept. of Mines, N.S.W. " Cane, J. E. Copper-Mining Industry of N.S.W.," Mines Dept., Geol. Surv., 1908; Mineral Resources of N.S.W. No. 6.

[32] Bain, [33]

:

:

:

:

,

[36]

[37]

Annual Reports of Under-Sec, for Mines, Queensland. " Silver Spur Mine," Queensland Govt. Min. Ball, L. C. :

Journ., 1918, pp. 152-60. " H. I. Arsenic Mines

[38] Jensen,

:

Govt.

Queensland '

Cameron, W. E.

"

in

Stanthorpe

District,"

Min. Journ., 1918, pp. 503-6.

Mount Prospect Silver-Lead Lode, Cania," Queensland Govt. Min. Journ., 1918, pp. 308-9. [40] Queensland Govt. Min. Journ., 1919. [39]

[41] '

[42]

:

Annual Rev. of Mining Operations in S. Australia. " J a ck, R. L. Geology of Moonta and Wallaroo Mining :

District," Geol. Surv. S. Australia, 1917, Bull. 6, p. 15. Annual [43] Reports of Direct, of Mines and Govt. Geologist of S. Australia, 1916.

REFERENCES TO LITERATURE ON SILVER [44]

Brown, H. V. p.

L.

149

Record of the Mines of S. Australia, 1908,

:

2.

[45] Jack,

R. L.

"Geology

:

of the

County

of Jerrois," etc., Geol.

Surv. S. Australia, 1914, Bull. 3, pp. 10-6. [46]

Annual Reports

"

[47] Reid, A. M.

:

of Secretary for Mines, Tasmania.

North Pieman and Huskisson and Sterling

Valley Mining Fields," Geol. Surv. Tasmania, 1918, Bull. 28. " Lead and Zinc Deposits of Read-Rosebery Dis[48] Hills, L. :

trict," Geol. Surv.

Tasmania, 1915, Bull. 19. " Scamander Mineral District," Geol. W. H. Twelvetrees, [49] Surv. Tasmania, 1911, Bull. 9. " Ore-Bodies of the [50] Twelvetrees, W. H., and Ward, L. K. Zeehan Field," Geol. Surv. Tasmania, 1910, Bull. 8. " Gladstone Mineral District," Geol. [51] Twelvetrees, W. H. :

:

:

Surv. Tasmania, 1916, Bull. 25. " Middlesex and Mt. Claude [52] Twelvetrees, W. H. Geol. Surv. Field," Tasmania, 1913, Bull. 14. :

Mining

M. "Mining Fields of Moina, Mt. Claude, and Lorinna," Geol. Surv. Tasmania, 1919, Bull. 29, p. 138. [54] Annual Reports of Secretary for Mines, Victoria. "Ore Deposits of Mexico II. Ore Deposits in [55] Lewis, S. J. Sedimentary Rocks. The Barreno and Ajuchitlan Mines," [53]

Reid, A.

:

:

Min. and

Sci. Press,

W. [57]

"

:

Mines, W.

Mining District,"

New

T.

:

Geol. Surv.

Report on Mines of Yilgarn Goldfield,"

Australia, 1908. "

Report on the Mines, W. Australia, 1908.

Montgomery, A.

[59] Blatchford, p. 121. [60]

27, 1920.

:

Montgomery, A. Dept.

[58]

March

"

Phillips River Australia, 1900, Bull. 5.

[56] Blatchford, T.

:

Geol.

W.

Surv.

Kanowna

Australia,

Mines," Dept.

1913,

Bull.

52,

Zealand Mines Statements (Annual).

New Zealand, 1910, Bull. 10. Kindelan, Vicente Estadistica Minera de Espana, 1908. Abstract in Min. Journ., Dec. 17, 1910, pp. 1461-2. " Mineral Deposits of Western Asia Minor," [63] Penzer, N. M. [61] Geol. Surv.

[62]

:

:

[64]

[65] [66]

Mining Magazine, Aug. 1919, pp. 76-81. " Notes on the Mines of the Ottoman Edwards, G. M. Trans. Inst. Min. and Met., 1914, 23, p. 197. Empire," Way, H. W. L. Mining Magazine, July 1916, pp. 22-3. Wheler, A. S., and Li, S. Y. "The Shui-Ko-Shan Zinc and :

:

:

Lead Mine," Mining Magazine, Feb. 1917,

pp. 91-7.

REFERENCES TO LITERATURE ON SILVER

i5o "

Mineral Resources"bf China," reprinted from the Far Eastern Review, July 1917, Mining Magazine, Oct. 1917, pp. 180-90. [68] The Twentieth Financial and Economic Annual of Japan,

[67]

[69]

Tokyo, 1920, p. J. M.

Maclaren,

53.

Gold

:

:

its

Geological

Occurrence and Geo-

graphical Distribution, London, 1908. "

*

[70]

-

[71]

Occurrence of Platinum in Wollastonite, Hundeshagen, L. on Island of Sumatra, Netherlands East Indies," Trans. Inst. Min. and Met., 1903-4, 13, pp. 550-2. :

"

Inouye, K.

Mineral Resources of Japan in 1908,"

:

Imp. Geol. Surv. of Japan, 1910, No. 2. " Mining in Japan, Past and Present," Bureau of [72] [73]

[74]

[75]

[77]

[78]

*

Mines, Dept.

:

:

W.

.

.

p. 1124.

[76]

of

of Agri. and Comm. of Japan, 1909. " Outlines of the Geology of Japan, pt. 3., Economic Geology," Imp. Geol. Surv. Japan, 1902. " Gold Mining Districts of Central Siberia," Brown, W. B. Trans. Amer. Inst. Min. Eng., 1904, 34, pp. 785-6. Guerin, Rene Revista Economica Boletin Mensual de Hacienda de Centro-America, Ano n, Mineria y Economia No. 9, April 1910, abstract in Min. Journ., Sept. 17, 1910, .

.

Mem.

.

.

.

"

Mining in Honduras," Trans. Amer. Min. Eng., 1892, 20, pp. 394-409. Mexican Year Book, 1909-10.

Thacer,

A.

:

Inst.

"

McCarthy, E. T. Mining in the Wollastonite Ore-Deposits of the Santa Fe Mine, Chiapas, Mexico," Trans. Inst. Min. and Met., 1895-6, 4, pp. 169-85. :

"

Some Silver-bearing Veins of [79] Halse, E. Inst. Min. Eng., 1901-2, 23, p. 310. :

[80] Halse,

"

E.

:

Mexico," Trans.

Notes on Structure of Ore-bearing Veins in

Mexico," Trans. Amer. Inst. Min. Eng., 32, p. 285. E. Trans. Inst. Min. Eng., 1900-1, 21, p. 198. Halse, [81] :

[82]

Mexican Min. Journ., Sept. 1909. (AbMin. Journ., pp. 48-9.) "El Mineral de Pachuca," Aguilera, J. G., and Ordonez, E.

Hijar y Haro, Luis.

:

stract in

[83]

:

Boletines del Instituto Geologico de Mexico, 1897.

:

:

-

Nos.

7,

8,9" El Real del Monte," Bole[84] Ordonez, E., and Rangel, Manuel tin del Instituto Geologico de Mexico, 1899, No. 12. [85] Burkart, J. Aufenthalt und Reisen in Mexico, 2 vols., 1836. Ramirez, [86] Santiago, Noticia Historica de la Riqueza Miner a de

Mexico, 1884.

REFERENCES TO LITERATURE ON SILVER

151

Trans. Inst. Min. Eng., 1903-4, 27, p. 169. Archives dela Commission [88] Dollfus, A., and Montserrat, E. de du 111, Mexique, 1864-69, p. 486-8. Scientifique Trans. Inst. Min. Eng., 1899-1900, 18. [89] Halse, E. [87] Halse, E.

:

:

:

[90] Dahlgren, C. B.

Minas

:

Historicas de la Republica Mexicana,

1887. [91]

Fuchs, Edmond, et Launay, L. de Traite des Gites Mineraux et Metalliferes, 1893, 2, pp. 818-20. :

Trans. Inst. Min. Eng., 1902-3, 24, p. 43. " Geological Analysis of the Silver Production [93] Lindgren, of U.S. in 1906," U.S. Geol. Surv., 1908, Bull. 340, pp. 23-35.

[92] Halse, E.

:

W.

[94]

:

Foreign Commerce and Navigation of U.S. f and Singewald, G. T. Mining in Potosi Dis'

[95] Miller, B. L. ,

trict," [96]

Gamba,

:

Eng. and Min. Journ., 1917, 103, pp. 255-60. Riqueza Mineral de la Republica de Colombia,

F. P.

:

1901. [97] Restrepo,

Vicente

:

Estudio sobre las

Minas

de Oro

y

Plata de

Colombia, 1888, pp. 41-2. [98] "Estadistica Minera del Peru," Bol. Cuerpo de Ing. de Minas. The Mineral [99] Miller, Benjamin L., and Singewald, Jr. Joseph T. South New America, York, 1919. Deposits of " El Mineral de Caracoles," Bol. de la Sociedad Nacional de [100] ,

:

Mineria, Series 3, 17, Santiago de Chile, Jan. 31, 1906. Abstract Min. Journ., June 30, 1906, p. 854. The Nature of Ore Deposits (Weed's trans.), [101] Beck, Richard New York, 1905, I, p. 279. " Observations on Metalliferous De[102] Henwood, W. Jory :

:

posits,"

Trans Roy.

Geol.

Soc. Cornwall, 8, Penzance, 1871,

pt. I, pp. 75-7. " El Mineral de Chanarcillo," Bol. [103] Echegarai, Nicomedes de la Soc. Nac. de Mineria, No. 106, Santiago de Chile, Dec. :

3i, 1905[104]

[105]

Min. Journ., May 5, 1906, p. 581. Herrmann, Alberto La Produccion en Chile de los Metales desde La Conquista hasta fines del Ano y Miner ales Abstract Min. Journ., 1902, Santiago de Chile, 1903. :

.

.

.

June 26, 1906. " Estado Actual de la Mineria en [106] Santolalla, F. Malaga del Bol. Cuerpo de Ing. de Minas del Peru, No. 75. Quiruvilca," Abstract Min. Journ., Oct. I, 1910, pp. Lima, 1909. :

1171-2. [107] Santolalla, F.

II

"

Malaga

:

Riquezas Minerales de

la Provincia

152

REFERENCES TO LITERATURE ON SILVER

de Santiago de Chuco," Bol. del Cuerpo de Ing. de Minas del Peru, No. 46, Lima, 1906. Abstract, Min. Jo-urn., Sept. and Oct. 28, 1907, pp. 388-9, 5, 1907, p. 440. Bol. del Cuerpo de Ing. de [108] De Romana, Eduardo A. L. Minas del Peru, No. 57, p. 33, Lima, 1908. " Estado Actual de la Mineria en [109] Jochamowitz, Albert :

:

Morococha ..." Bol. del Cuerpo de Ing. de Minas del Abstract Min. Journ., May Peru, No. 65, Lima, 1908. 22, 1909, p. 644.

"

Fisionomia Minera de les Provincias [no] Duefias, Enrique J. de Tayacaja, Angaraes y Huancavelica," Bol. del Cuerpo de Ing. de Minas del Peru, No. 62, Lima, 1908. Abstract Min. Journ., March 27, 1909, pp. 399-400, and April 10, :

1909, pp. 459-60.

"

Aspecto Minero del Departmento de Cuzco," Bol. del Cuerpo de Ing. de Minas del Peru, No. Abstract Min. Journ., March 7, 1908, 53, Lima, 1907.

[in] Duenas, Enrique

J.

:

p. 284, and March 14, 1908, pp. 315-6. " Recursos Minerales del Departa[112] Jochamowitz, Alberto mento de Apurimac," Bol. del Cuerpo de Ing. de Minas del :

Peru, No. 58, Lima, 1908. 1908, p. 603.

Abstract Min. Journ., Nov.

"

7,

Estado Actual y Porvenir de la Departamentos del Sur," Bol. del del Peru, No. 93, Lima, 1918. de Minas de Ing. Cuerpo Abstract Min. Journ., May 17, 1919, pp. 301-2. Informaciones i Memorias, Organo de la Soc. [114] Carroll, C. M. de Ing. del Peru, Lima, Dec. 1908, pp. 479-503. Abstract Min. Journ., Oct. 23, 1909, p. 129. The Mines Handbook, New York, [115] Weed, Walter Harvey [113]

Basadre y G., Carlos Industria Minera en

:

los

:

:

1920, p. 1792.

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